Wireless power transmitter

ABSTRACT

A wireless power transmitter includes a converter comprising at least one switching element, and configured to generate boosted input power; a resonator and a controller. The resonator is configured to receive the boosted input power as an alternating current (AC) power, and transmit a ping signal in a detection mode for determining whether any one or both of an external object approaching and a type of the external object. The controller is configured to control the switching element, and gradually increase a duty cycle of a gate signal provided to the switching element, in the detection mode.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit under 35 U.S.C. § 119(a) of KoreanPatent Application Nos. 10-2016-0131880 and 10-2016-0153568 filed onfiled on Oct. 12, 2016 and Nov. 17, 2016, respectively, in the KoreanIntellectual Property Office, the entire disclosures of which areincorporated herein by reference for all purposes.

BACKGROUND 1. Field

The present disclosure relates to a device for transmitting powerwirelessly.

2. Description of Related Art

Recently, many mobile devices that are charged in a wireless manner havebeen introduced. Accordingly, many wireless power transmitters forwirelessly transmitting power to mobile devices have been introduced.With such wireless power transmission devices, research is beingconducted into reducing material costs, satisfying various requirements,and improving wireless power transmission efficiency. Research intoimproving user convenience and wireless power transmission efficiencywhile satisfying various requirements are also being carried out.

SUMMARY

An aspect of the present disclosure may provide a wireless powertransmitter transmitting power wirelessly.

In one general aspect, a wireless power transmitter includes a convertercomprising at least one switching element, and configured to generateboosted input power; a resonator and a controller. The resonator isconfigured to receive the boosted input power as an alternating current(AC) power, and transmit a ping signal in a detection mode fordetermining whether any one or both of an external object approachingand a type of the external object. The controller is configured tocontrol the switching element, and gradually increase a duty cycle of agate signal provided to the switching element, in the detection mode.

The controller may gradually increase the duty cycle of the gate signalin an amount equal to a reference duty cycle.

The controller may increase the duty cycle of the gate signal from afirst duty cycle of 0%, in an initial operation mode of the detectionmode.

The initial operation mode may correspond to a mode for transmitting theping signal in a stop state for a time equal to or greater than areference time.

The controller may increase the duty cycle of the gate signal to a pingduty cycle, and the boosted input power to reach a target boosted inputpower for generating the ping signal in the ping duty cycle.

The controller may be further configured to calculate data on a voltagelevel of the boosted input power gradually increasing to the targetboosted input power, and a duty cycle corresponding to the voltage levelof the boosted input power gradually increases.

The controller may be further configured to increase the duty cycle ofthe gate signal from a second duty cycle, in a standby operation mode ofthe detection mode, and the second duty cycle is determined based on thevoltage level of boosted input power.

The standby operation mode may correspond to a mode for transmitting aping signal in the stop state for less than the reference time.

The voltage level of the boosted input power may be estimated based on aperiod of the ping signal.

The second duty cycle may be calculated based on the voltage level ofthe boosted input power and the data.

The second duty cycle may be determined by applying a weighted index,calculated by comparing a voltage level of the target boosted inputpower to the voltage level of the boosted input power, to the ping dutycycle.

The data may be provided in the form of a lookup-table, and the secondduty cycle may be determined by searching through the lookup-table for aduty cycle corresponding to the voltage level of the boosted inputpower.

In another general aspect, a wireless power transmitter operated in adetection mode including a first mode and a second mode, andtransmitting a ping signal in the detection mode, the transmittingwireless power transmitter, includes a converter, a resonator, and acontroller. The converter includes at least one switching element, andis configured to convert input power into boosted input power based on aswitching operation of the switching element, and output the boostedinput power as an alternating current (AC) power. The resonator isconfigured to generate the ping signal from the AC power. The controlleris configured to control the switching element, increase a duty cycle ofa gate signal provided to the switching element from a first duty cyclein the first mode, and increase a duty cycle of the gate signal from asecond duty cycle higher than the first duty cycle in the second mode.

The controller may be further configured to increase the duty cycle ofthe gate signal to a ping duty cycle in the first mode, and the boostedinput power may reach a target boosted input power for generating theping signal in the ping duty cycle.

The second duty cycle may be determined based on a weighted index,calculated by comparing a voltage level of the target boosted inputpower to a voltage level of the boosted input power, to the ping dutycycle.

The switching element may be configured to perform a convertingoperation from the boosted input power to the input power and anoutputting operation from the boosted input power as AC power.

In another general aspect, a wireless power transmitter includes aconverter, a resonator, and a controller. The converter is configured togenerate an alternating current (AC) voltage. The resonator isconfigured to receive the AC voltage, and transmit a ping signal fordetermining whether an external object is within proximity. Thecontroller is configured to control the switching element, and increasea duty cycle of a gate signal provided to the switching element by astep size from a first duty cycle to a target duty cycle.

The step size is an integer and the first duty cycle may be 0%.

The initial operation mode may correspond to a mode for transmitting theping signal in a stop state for a time equal to or greater than areference time.

According to an aspect of the present disclosure, a wireless powertransmitter may include a converter including at least one switchingelement, and boosting input power and then generating boosted inputpower, a resonator receiving the boosted input power in the form ofalternating current (AC) power from the converter, and transmitting aping signal in a detection mode for determining at least one of whetheror not an external object is approaching and the type of the externalobject, and a controller controlling the at least one switching element,wherein the controller gradually increases a duty of a gate signalprovided for the at least one switching element, in the detection mode.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a diagram schematically illustrating an application of awireless power transmitter, according to an embodiment.

FIG. 2 is a diagram schematically illustrating a wireless powertransmission method, according to an embodiment.

FIG. 3 is a diagram illustrating a change in an operation of thewireless power transmitter for transmitting power required by a wirelesspower receiver depending on the distance between the wireless powertransmitter and the wireless power receiver.

FIG. 4 is a diagram illustrating a change in an operation of thewireless power transmitter for transmitting power required by thewireless power receiver depending on the degree of alignment between thewireless power transmitter and the wireless power receiver.

FIG. 5 is a diagram illustrating a change in an operation of thewireless power transmitter for transmitting power required by thewireless power receiver depending on the amount of charge of a batteryof the wireless power receiver.

FIG. 6 is a diagram illustrating a relationship between a voltage gainand an operating frequency between a transmission coil of the wirelesspower transmitter and a reception coil of the wireless power receiver.

FIGS. 7 through 15 are diagrams each schematically illustrating aconfiguration of a wireless power transmitter, according to embodiments.

FIG. 16 is a flowchart illustrating an operation in an initial operationmode of the wireless power transmitter and the wireless powertransmission method, according to an embodiment.

FIG. 17 is an operation flowchart illustrating an operation in a standbyoperation mode of the wireless power transmitter and the wireless powertransmission method, according to an embodiment.

FIG. 18 is a diagram illustrating a change of a boost voltage in theinitial operation mode and the standby operation mode of the wirelesspower transmitter and the wireless power transmission method, accordingto an embodiment.

FIGS. 19 through 24 are waveform diagrams respectively illustratingoperations of the wireless power transmitter and the wireless powertransmission method in a power transmission mode. The waveform diagramsrepresent waveforms of control signals that control switching elementsof the wireless power transmitter.

FIGS. 25 and 26 are diagrams each schematically illustrating a processof changing adjusted variables in the wireless power transmitter and thewireless power transmission method, according to an embodiment.

FIGS. 27 through 46 are operation flowcharts each illustrating anoperation of the wireless power transmitter and the wireless powertransmission method in a power transmission mode, according to anembodiment, and diagrams respectively illustrating a change of anoperating frequency and an operating duty cycle.

FIGS. 47A and 47B are diagrams illustrating a coil current and an outputvoltage of the wireless power transmitter, according to an embodiment.

FIGS. 48A and 48B are diagrams illustrating a boost voltage and anoutput voltage based on a change of a duty cycle in the wireless powertransmitter, according to an embodiment.

Throughout the drawings and the detailed description, the same referencenumerals refer to the same elements. The drawings may not be to scale,and the relative size, proportions, and depiction of elements in thedrawings may be exaggerated for clarity, illustration, and convenience.

DETAILED DESCRIPTION

The following detailed description is provided to assist the reader ingaining a comprehensive understanding of the methods, apparatuses,and/or systems described herein. However, various changes,modifications, and equivalents of the methods, apparatuses, and/orsystems described herein will be apparent after an understanding of thedisclosure of this application. For example, the sequences of operationsdescribed herein are merely examples, and are not limited to those setforth herein, but may be changed as will be apparent after anunderstanding of the disclosure of this application, with the exceptionof operations necessarily occurring in a certain order. Also,descriptions of features that are known in the art may be omitted forincreased clarity and conciseness.

The features described herein may be embodied in different forms, andare not to be construed as being limited to the examples describedherein. Rather, the examples described herein have been provided merelyto illustrate some of the many possible ways of implementing themethods, apparatuses, and/or systems described herein that will beapparent after an understanding of the disclosure of this application.

Throughout the specification, when an element, such as a layer, region,or substrate, is described as being “on,” “connected to,” or “coupledto” another element, it may be directly “on,” “connected to,” or“coupled to” the other element, or there may be one or more otherelements intervening therebetween. In contrast, when an element isdescribed as being “directly on,” “directly connected to,” or “directlycoupled to” another element, there can be no other elements interveningtherebetween.

As used herein, the term “and/or” includes any one and any combinationof any two or more of the associated listed items.

Although terms such as “first,” “second,” and “third” may be used hereinto describe various members, components, regions, layers, or sections,these members, components, regions, layers, or sections are not to belimited by these terms. Rather, these terms are only used to distinguishone member, component, region, layer, or section from another member,component, region, layer, or section. Thus, a first member, component,region, layer, or section referred to in examples described herein mayalso be referred to as a second member, component, region, layer, orsection without departing from the teachings of the examples.

The terminology used herein is for describing various examples only, andis not to be used to limit the disclosure. The articles “a,” “an,” and“the” are intended to include the plural forms as well, unless thecontext clearly indicates otherwise. The terms “comprises,” “includes,”and “has” specify the presence of stated features, numbers, operations,members, elements, and/or combinations thereof, but do not preclude thepresence or addition of one or more other features, numbers, operations,members, elements, and/or combinations thereof.

Due to manufacturing techniques and/or tolerances, variations of theshapes shown in the drawings may occur. Thus, the examples describedherein are not limited to the specific shapes shown in the drawings, butinclude changes in shape that occur during manufacturing.

The features of the examples described herein may be combined in variousways as will be apparent after an understanding of the disclosure ofthis application. Further, although the examples described herein have avariety of configurations, other configurations are possible as will beapparent after an understanding of the disclosure of this application.

FIG. 1 is a diagram schematically illustrating an application of awireless power transmitter 1, according to an embodiment.

Referring to FIG. 1, the wireless power transmitter 1 and a wirelesspower receiver 2 are magnetically coupled to each other to wirelesslytransmit and receive power. As an example, the wireless powertransmitter 1 and the wireless power receiver 2 are coupled to eachother by magnetic resonance and/or magnetic induction.

The wireless power receiver 2 provides the received power to anelectronic device 3. The electronic device 3 performs an operation, suchas charging an internal battery using the power provided by the wirelesspower receiver 2. The wireless power receiver 2 is present in theelectronic device 3 as one component, or may be a separate deviceconnected to the electronic device 3.

Referring to FIG. 1, the wireless power receiver 2 is disposed in aposition adjacent to the wireless power transmitter 1, but the relativedistance and/or alignment from the wireless power transmitter 1 to thewireless power receiver 2 may be changed. The wireless power transmitter1 may be operated in boost mode to stably transmit power to the wirelesspower receiver 2 in situations where the wireless power receiver 2 doesnot sufficiently receive required power due to increased distance ormisalignment from the wireless power transmitter 1 and the wirelesspower receiver 2, large amount of power is required due to the batteryof the electronic device 3 being close to a discharged state, and/or inother required cases. Alternatively, the wireless power transmitter 1may be operated in a reduction mode to prevent unnecessary powerconsumption and prevent overheating of the wireless power receiver 2and/or the electronic device 3 in situations where the wireless powerreceiver 2 receives required power or more than the required power dueto the distance from the wireless power transmitter 1 being decreased orthe alignment between the wireless power transmitter 1 and the wirelesspower receiver 2 improves, in a case in which a reduced amount of poweris required due to the battery of the electronic device 3 being close toa fully charged state.

FIG. 2 is an operation flowchart schematically illustrating a method forwirelessly transmitting power, according to an embodiment.

The wireless power transmission method of FIG. 2 may be performed by thewireless power transmitter 1. Although the flowchart of FIG. 2 isillustrated in a sequential time order, the order of some operations maybe modified or some operations may be omitted, and some phases may alsobe periodically repeated. As an example, the wireless power transmitter1 periodically enters an analog ping phase (S10) and a digital pingphase (S20).

Referring to FIGS. 1 and 2, the wireless power transmission methodbegins by the wireless power transmitter 1 entering the analog pingphase (S10).

In the analog ping phase, the wireless power transmitter 1 transmits ananalog ping signal. In a case in which an impedance level of the analogping signal changes, the wireless power transmitter 1 determines that anexternal object is positioned around the wireless power transmitter 1.For example, the wireless power transmitter 1 transmits the analog pingsignal through a transmission coil or other coils, and determineswhether the external object is positioned around the wireless powertransmitter 1 using a change in impedance of the coil that transmits theanalog ping signal or a change in the level of the analog ping signal.The analog ping signal may be transmitted according to a set period.

In a case in which it is determined that a predetermined external objectis adjacent to the wireless power transmitter 1 in the analog pingphase, the wireless power transmitter 1 enters the digital ping phase(S20). Alternatively, the wireless power transmitter 1 enters thedigital ping phase based on a set period. The wireless power transmitter1 transmits a digital ping signal in the digital ping phase to determinewhether the external object, which is adjacent to the wireless powertransmitter 1, is the wireless power receiver. For example, the wirelesspower transmitter 1 determines whether the external object adjacentthereto is the wireless power receiver depending on whether a responsesignal is received from the wireless power receiver 2, aftertransmitting the digital ping signal.

The wireless power transmitter 1 enters an identification andconfiguration phase (S30) in response to receiving the response signalof the wireless power receiver for the digital ping signal. In a case inwhich the external object is the wireless power receiver, the wirelesspower receiver transmits the response signal for the received digitalping signal. The response signal of the wireless power receiver includesany one or any combination of information regarding signal strength, akind of the wireless power receiver, input voltage strength, powerrequired by the wireless power receiver, and an error value indicating adifference between the power required by the wireless power receiver andpower received by the wireless power receiver. Therefore, the wirelesspower transmitter 1 confirms a target and a power demand using theresponse signal of the wireless power receiver for the digital pingsignal.

Thereafter, the wireless power transmitter 1 enters a power transferphase (S40), in which the wireless power transmitter 1 wirelesslyprovides the power to the wireless power receiver using the informationconfirmed in the identification and configuration phase (S30).

In the power transfer phase (S40), the wireless power transmitter 1 isoperated in a normal mode, a boost mode, or a reduction mode.

The normal mode is, for example, an operation mode in which a dutycycle, or “duty” for short, of a control signal for controlling aswitching element of the wireless power transmitter 1 is fixed to anyvalue, and an operating frequency of the wireless power transmitter 1 isvaried within a preset reference range. The value to which the dutycycle is fixed may be a duty cycle of a control signal generated totransmit the above-mentioned analog ping and/or digital ping signals,and other signals for determining whether the wireless power receiver ispresent. The reference range of the operating frequency may be afrequency range usable by a defined standard, determined by consideringthe degree of heat generated in the wireless power receiver, of aspatial region to be charged using the wireless power transmitter withinthe usable frequency range, or determined by considering power transfercharacteristics between the wireless power transmitter 1 and thewireless power receiver 2.

The boost mode is, for example, an operation mode of the wireless powertransmitter 1 in which the wireless power receiver 2 is operated toreceive a larger amount of power in comparison to the normal mode. Thewireless power transmitter 1 may adjust the duty cycle or adjust theoperating frequency to be lower than the reference range to allow thewireless power receiver 2 to receive a larger amount of power.

The reduction mode is, for example, an operation mode of the wirelesspower transmitter 1 in which the wireless power receiver 2 is operatedto receive a smaller amount of power in comparison to the normal mode.The wireless power transmitter 1 may adjust the duty cycle or adjust theoperating frequency to be greater than the reference range to allow thewireless power receiver 2 to receive a smaller amount of power.

Although FIG. 2 illustrates a case in which the wireless powertransmitter 1 uses the analog ping signal and the digital ping signal todetermine whether the wireless power receiver 2 is present. The wirelesspower transmitter 1 may also determine whether the wireless powerreceiver 2 is present by using a signal other than the ping signals.

In addition, although FIG. 2 illustrates a case in which the wirelesspower transmitter 1 performs the analog ping phase and the digital pingphase to determine whether the wireless power receiver 2 is present, thewireless power transmitter 1 may also determine whether the wirelesspower receiver 2 is present in a different manner. For example, thewireless power transmitter 1 may determine whether the wireless powerreceiver 2 is present by using a separate local area communicationscircuit, such as Bluetooth, and may also determine whether the externalobject is adjacent to the wireless power transmitter 1 and whether theadjacent object is the wireless power receiver through one phase orthree or more phases.

FIG. 3 is a diagram illustrating a changed operation of the wirelesspower transmitter 1 based on a distance between the wireless powertransmitter 1 and the wireless power receiver 2, and illustrates theelectronic device 3 including the wireless power receiver 2 and thewireless power transmitter 1.

FIG. 3 illustrates situations (a1) through (c1). Situation (a1)illustrates a case in which the wireless power receiver 2 is mounted onthe wireless power transmitter 1, situation (b1) illustrates a case inwhich the wireless power receiver 2 is spaced apart from the wirelesspower transmitter 1 by a spacing threshold distance Dt or less, andsituation (c1) illustrates a case in which the wireless power receiver 2is spaced apart from the wireless power transmitter 1 by the spacingthreshold distance Dt or more.

In situation (c1), as compared to situation (a1) or situation (b1), inorder for the wireless power receiver 2 to receive a required amount ofpower, the wireless power transmitter 1 needs to transmit a largeramount of power. Conversely, in the case of situation (a1), as comparedto situation (b1) or situation (c1), even when the wireless powertransmitter 1 transmits the least amount of power, the wireless powerreceiver 2 receives the required amount of power.

In the example illustrated in FIG. 3, the spacing threshold distance Dtis an effective charging distance at the time of transmission at maximumpower in the normal mode.

When the distance between the wireless power transmitter and thewireless power receiver is equal to the spacing threshold distance orless, the wireless power transmitter 1 is operated in the normal mode.That is, in situation (a1) and/or situation (b1), the wireless powertransmitter 1 is operated in the normal mode in which the duty cycle isfixed and the operating frequencies of the switches are changed toadjust an output.

However, when the distance between the wireless power transmitter 1 andthe wireless power receiver 2 is greater than the spacing thresholddistance, the wireless power transmitter 1 is operated in the boost modeto compensate for the distance. That is, in situation (c1), the wirelesspower transmitter 1 adjusts the duty cycle, and/or the operatingfrequency.

Alternatively, the wireless power transmitter 1 is operated in thenormal mode in situation (b1), and in the reduction mode in situation(a1).

FIG. 4 is a diagram illustrating a changed operation of the wirelesspower transmitter 1 based on a degree of alignment between the wirelesspower transmitter 1 and the wireless power receiver 2, and illustratesthe electronic device 3 including the wireless power receiver 2 and thewireless power transmitter 1.

FIG. 4 illustrates situation (a2) through situation (c2). In situation(a2), the center of the wireless power receiver 2 and the center of thewireless power transmitter 1 coincide with each other. In situation(b2), the center of the wireless power receiver 2 and the center ofwireless power transmitter 1 are misaligned by a distance L1, which isless than or equal to a spacing threshold distance Lt. Situation (c2)illustrates a case in which misalignment between the center of thewireless power receiver 2 and the center of wireless power transmitter 1are spaced apart by a distance L2, which is greater than or equal to thespacing threshold distance Lt.

In the case of situation (c2), as compared to situation (a2) orsituation (b2), in order for the wireless power receiver 2 to receivethe required amount of power, the wireless power transmitter 1 needs totransmit a larger amount of power. Conversely, in the case of situation(a2), as compared to situation (b2) or situation (c2), even though thewireless power transmitter 1 transmits the least amount of power, thewireless power receiver 2 receives the required amount of power.

In the illustrated example, the spacing threshold distance Lt representsan effective charging distance, at the time of transmission, at maximumpower in the normal mode.

Similarly to the situations described in FIG. 3, in situation (a2)and/or situation (b2), the wireless power transmitter 1 is operated inthe normal mode. In situation (c2), the wireless power transmitter 1 isoperated in the boost mode. Alternatively, in situation (a2), thewireless power transmitter 1 is also operated in the reduction mode.

FIG. 5 is a diagram illustrating a changed operation of the wirelesspower transmitter 1 based on an amount of charge of a battery of thewireless power receiver 2.

In situation where the amount of charge of the battery approaches a fullcharge state (situation (a3)), the wireless power receiver requires theleast amount of power. In a case in which the amount of charge of thebattery approaches a discharge state (situation (c3)), the wirelesspower receiver requires a larger amount of power.

The wireless power transmitter 1 determines the operation mode inresponse to the signal received from the wireless power receiver 2. Inthis case, the wireless power transmitter is operated in the normal modein situation (b3), the boost mode in situation (c3), and the reductionmode in situation (a3).

FIG. 6 is a diagram illustrating a relationship between a voltage gainand an operating frequency between a transmission coil of the wirelesspower transmitter and a reception coil of the wireless power receiver,wherein the X axis represents the operating frequency and the Y axisrepresents the voltage gain.

Referring to FIG. 6, in normal mode, the wireless power transmitterfixes the duty cycle of the switches and adjusts the operating frequencybetween a first reference frequency f1 and a second reference frequencyf2. The duty cycle in the normal mode may be the duty cycle of thesignal used by the wireless power transmitter to determine whether thewireless power receiver is present. In normal mode, when the wirelesspower receiver 2 is somewhat distant from the wireless power transmitter1 or requires a larger amount of power, the wireless power transmitterincreases the amount of power received by the wireless power receiver 2by decreasing the frequency. Alternatively, in the normal mode, when thewireless power receiver 2 is somewhat closer to the wireless powertransmitter 1 or requires a smaller amount of power, the wireless powertransmitter 1 decreases the amount of power received by the wirelesspower receiver 2 by increasing the frequency.

Also, when the amount of power required by the wireless power receiver 2is higher than the maximum value of power that the wireless powerreceiver 2 receives in normal mode, the wireless power transmitter 1changes the operation mode to the boost mode so that the wireless powerreceiver 2 receives an amount of power equal to or more than an amountof power receivable by the wireless power receiver 2 in the normal mode.In this case, the operating frequency of the wireless power transmitteris fixed to the first reference frequency f1, and the duty cycle isadjusted. Further, when the amount of power received by the wirelesspower receiver is not sufficiently large, even when the duty cycle isincreased to a limit value of a defined range, the wireless powertransmitter 1 additionally decreases the operating frequency afterfixing the duty cycle to the limit value. A detailed operation in theboost mode will be described below.

In addition, when the amount of power required by the wireless powerreceiver 2 is lower than the minimum value of the power that thewireless power receiver 2 receives in the normal mode, the wirelesspower transmitter 1 changes the operation mode to the reduction mode. Inthis case, the operating frequency of the wireless power transmitter 1is fixed to the second reference frequency f2, and the duty cycle isadjusted. Alternatively, the wireless power transmitter may operate as afull bridge and then also operate as a half bridge. A detailed operationin the reduction mode will be described below.

The first reference frequency f1 and the second reference frequency f2may each be equal to each of the minimum frequency f_min and the maximumfrequency f_max. The minimum frequency f_min and the maximum frequencyf_max may each be a lower limit value and an upper limit value of ausable frequency range defined by standards or other protocols.Alternatively, the first reference frequency f1 and the second referencefrequency f2 may also be determined based on the degree of heatgenerated in the wireless power receiver 2 or a range of a spatialregion to be charged using the wireless power transmitter 1 in the rangeof the minimum frequency f_min to the maximum frequency f_max. Bydetermining the first reference frequency f1 and the second referencefrequency f2 as described above, the wireless power transmitter 1operates more stably within a defined range, and prevents damage orover-heating of an element in the wireless power receiver 2.

Alternatively, the first reference frequency f1 and the second referencefrequency f2 are also determined by considering power transfercharacteristics between the wireless power transmitter 1 and thewireless power receiver 2 in the range of the minimum frequency f_min tothe maximum frequency f_max.

In a case in which the operating frequency is within a predeterminedrange between frequency value f2 and f_max as illustrated in FIG. 6,since a change of the gain value with respect to a change of thefrequency value has a gradual slope, it is easier to control thewireless power transmitter 1 so that the wireless power receiver 2receives an appropriate amount of power. However, since a change of thegain value with respect to a change of the operating frequency value islarge when the operating frequency falls to a predetermined thresholdfrequency value f1 or less, and the change of the gain with respect tothe change of the operating frequency may be excessively small when theoperating frequency reaches a predetermined threshold value f2 or more,it is not easy to control the wireless power transmitter 1 so that thewireless power receiver 2 receives an appropriate amount of power.

In consideration of the above-mentioned aspects, when the wireless powertransmitter 1 is operated in normal mode, the first reference frequencyf1 and the second reference frequency f2 are determined so that a changeof the gain value with respect to a change of the operating frequencyvalue is within a reference range. That is, referring to the graphillustrated in FIG. 6, the first reference frequency f1 is determined asa frequency at which the change of the gain value with respect to thechange of the frequency value in the range of the minimum frequencyf_min to the maximum frequency f_max is a predetermined maximum value.The second reference frequency f2 is determined as a frequency at whichthe change of the gain value with respect to the change of the frequencyin the range of the minimum frequency f_min to the maximum frequencyf_max is a predetermined minimum value.

By determining the first reference frequency f1 and the second referencefrequency f2 as described above, the wireless power transmitter 1prevents damage and/or over-heating of an element in the wireless powerreceiver 2, and more precisely controls power transmissions to thewireless power receiver.

The first reference frequency f1 and the second reference frequency f2may be experimentally determined and set in advance, or may be inputexternally. Alternatively, the first reference frequency f1 and thesecond reference frequency f2 are also set or changed in the wirelesspower transmitter 1 after the wireless power transmitter 1 is operated.In order to set or change the first reference frequency f1 and thesecond reference frequency f2, the wireless power transmitter 1 may alsoperform a predetermined algorithm, and may also include an additionalhardware configuration for this purpose.

In addition, as illustrated in FIG. 6, the voltage gain has a maximumvalue at a resonance frequency f_r. The resonance frequency f_r is aresonance frequency of a resonator of the wireless power transmitter tobe described below. In this case, the minimum frequency f_min is about110% of the resonance frequency f_r, and the maximum frequency f_max isabout 150% of the resonance frequency f_r.

FIG. 7 is a block diagram schematically illustrating a configuration ofthe wireless power transmitter 1 including a circuit unit 100 and acontroller 200, according to an embodiment. The circuit unit 100includes a converter 110 and a resonator 120. In FIG. 7, referencenumeral 300 denotes an input power source.

The circuit unit 100 is provided with an input voltage Vin from theinput power source 300, and wirelessly transmits the power in responseto at least one control signal con. An amount and frequency of the powerwirelessly transmitted is varied by the control signal con.

The converter 110 converts the input voltage Vin into an alternatingcurrent (AC) voltage Vac in response to the control signal con, andoutputs the converted AC voltage. Amplitude and frequency of the ACvoltage Vac are determined based on the control signal con. For example,the amplitude of the AC voltage Vac is determined based on a duty cycleof the control signal con (when there are a plurality of control signalscon, the duty cycle of some or all of the control signals con determinesthe amplitude of the AC voltage Vac). In addition, the frequency of theAC voltage Vac is determined based on a frequency of the control signalcon (when there are a plurality of control signals con, the frequency ofsome or all of the control signals con determines the frequency of theAC voltage Vac).

The frequency of the AC voltage Vac may be greater than the resonancefrequency f_r (FIG. 6) of the resonator 120. For example, the frequencyof the AC voltage Vac may also be determined to be between about 110% toabout 150% of the resonance frequency f_r (FIG. 6) of the resonator 120.

The converter 110 may be implemented in various forms. For example, theconverter 110 may also include a boost converter and an inverter, mayalso include only the inverter, and may also include a boost inverterthat performs both the function of the boost converter and the functionof the inverter.

The resonator 120 is provided with the AC voltage Vac, and transmits asignal for determining whether the wireless power receiver 1 is presentusing the analog ping signal or the digital ping signal. The resonator120 wirelessly transmits the signal and/or the power by changing asurrounding magnetic field based on the AC voltage Vac. The resonator120 may include a resonance capacitor and a resonance coil, and theresonance frequency f_r (FIG. 6) of the resonator 120 may be determinedby capacitance of the resonance capacitor and inductance of theresonance coil.

The controller 200 outputs at least one control signal con in responseto a request signal req. The controller 200 adjusts a duty cycle and/ora frequency of the control signal con in response to the request signalreq. The request signal req is input from the wireless power receiver 2,and represents an amount of power required by the wireless powerreceiver 2. For example, the request signal req may be a signalrequesting an amount of power wirelessly transmitted by the wirelesspower transmitter 1 to increase, or may be a signal requesting theamount of power to decrease. Alternatively, the request signal req isalso a signal representing a difference between the amount of powerrequired by the wireless power receiver and an amount of power actuallyreceived by the wireless power receiver. The controller 200 determineswhether to increase or decrease the amount of transmitted power based onthe request signal req, and adjusts an operating duty cycle and anoperating frequency of the control signal con accordingly.

For example, the controller 200 adjusts the operating frequency in thenormal mode. In the boost mode or the reduction mode, the controller 200adjusts the operating duty cycle or both the operating duty cycle andthe operating frequency. For example, in the normal mode, the controller200 decreases the frequency when a distance between the wireless powerreceiver 2 and the wireless power transmitter 1 increases, and increasesthe frequency when the distance decreases. In the boost mode or thereduction mode, the controller 200 increases the duty cycle when thedistance between the wireless power receiver 2 and the wireless powertransmitter 1 increases, and decreases the duty cycle when the distancedecreases.

As an example, when the operating frequency corresponds to a lowestreference frequency and a normal mode operation is performed, if therequest signal req requests the amount of power to increase, thecontroller 200 performs controlling so that the operation mode isswitched from the normal mode to the boost mode.

As another example, when the operating duty cycle corresponds to alowest reference duty cycle and a boost mode operation is performed, ifthe request signal req requests the amount of power to decrease, thecontroller 200 performs controlling so that the operation mode isswitched from the boost mode to the normal mode.

A detailed operation of the controller 200 and controllers 201-208,according to additional embodiments, will be described below withreference to FIGS. 16 through 46.

As shown in FIG. 7, controller 200 includes at least one processor 200a. According to an embodiment, the controller 200 further includes amemory 200 b. The processor 200 a may include, a central processing unit(CPU), a graphics processing unit (GPU), a microprocessor, anapplication specific integrated circuit (ASIC), and/or fieldprogrammable gate arrays (FPGAs), and may have a plurality of cores. Thememory 200 b may be a volatile memory (e.g., a random access memory(RAM)), a non-volatile memory (e.g., a read only memory (ROM) or a flashmemory), or a combination thereof. A program including instructionsconfigured to perform a wireless power transmission method according maybe stored in the memory.

The controller 200 may include a gate driver. Alternatively, thewireless power transmitter 1 separately includes the gate driver fordriving switches included in the converter 110 based on the controlsignal con provided by the controller 200.

The input power source 300 outputs the input voltage Vin. For example,the input power source 300 is an adapter that converts an alternatingcurrent (AC) voltage input from the outside into a direct current (DC)voltage and outputs the converted DC voltage. A level of the inputvoltage Vin output from the input power source 300 may be one of variousvoltage levels which are standardized in a wireless power transmissionand reception system. For example, the input voltage is one of 5V, 9V,and 12V.

FIG. 8 is a diagram schematically illustrating a configuration of awireless power transmitter 1-1 including a circuit unit 101 and acontroller 201, according to an embodiment. The circuit unit 101includes a converter 111 and a resonator 121. The converter 111 includesswitching elements Q11 and Q21, a first coil L11, and a first capacitorC11. The resonator 121 includes a second capacitor C21 and a second coilL21.

Functions of the circuit unit 101, the converter 111, the resonator 121,the controller 201, and the input power source 300 are substantially thesame as those of the circuit unit 100, the converter 110, the resonator120, the controller 200, and the input power source 300, respectively,described in FIG. 7.

An amplitude of the AC voltage output from the converter 111 isdetermined based on magnitude of a voltage of a second node N2, that is,a boost voltage. The magnitude of the boost voltage Vboost is determinedby Equation 1.

Vboost=Vin/(1−D)  [Equation 1]

In Equation 1, Vin is a magnitude of a voltage of power input from theinput power source 300, and D is an ON-duty cycle of a second controlsignal con21.

The duty cycle in the boost mode is greater than the duty cycle in thenormal mode. Therefore, a boost voltage in the boost mode is greaterthan a boost voltage in the normal mode, and consequently, the amount ofpower transmitted by the wireless power transmitter 1-1 in the boostmode is greater than an amount of power transmitted by the wirelesspower transmitter 1-1 in the normal mode.

In addition, a voltage of a first node N1 is the AC voltage output fromthe converter 111, and the AC voltage Vinv(t) output from the converter111 is determined by Equation 2.

Vinv(t)=2(Vin/(1−D))sin(wt/π)  [Equation 2]

In Equation 2, w denotes a frequency of a first control signal con11 andthe second control signal con21.

The first coil L11 is connected between a terminal to which the inputvoltage is applied and the first node N1. The first switching elementQ11 is connected between the first node N1 and the second node N2. Thesecond switching element Q21 is connected between the first node N1 anda ground terminal. The first capacitor C11 is connected between thesecond node N2 and the ground terminal. The AC voltage generated by theconverter 111 is output to the first node N1. The voltage of the secondnode N2 is a boost voltage obtained by boosting the input voltage by theconverter 111. The first switching element Q11 is turned on and off inresponse to the first control signal con11, and the second switchingelement Q21 is turned on and off in response to the second controlsignal con21. In addition, the first switching element Q11 and thesecond switching element Q21 are turned on and off complementarily witheach other.

In other words, the converter 111 includes a bridge circuit, and thebridge circuit includes the first switch Q11 and the second switch Q21connected in series with each other and alternately operated. Oneterminal of the inductor L11 is connected to one terminal of the inputpower source 300, and the other terminal of the inductor L11 isconnected to a connection terminal (node N1) between the first andsecond switches. One terminal of the output capacitor C11 is connectedto one terminal of a half-bridge circuit, and the other terminal of theoutput capacitor C11 is connected to the other terminal of the inputpower source 300 and the other terminal of the half-bridge circuit.

That is, the converter 111 simultaneously functions as the boostconverter that boosts the input voltage to the boost voltage based onthe duty cycle of the control signals con11 and con21, and as theinverter that converts the DC voltage into the AC voltage. Specifically,the switching elements Q11 and Q12, the first capacitor C11, and thefirst coil L11 are operated as the boost converter. In addition, theswitching elements Q11 and Q12 are also operated as the inverter. Inother words, the converter 111 includes a boost inverter having a formin which the boost converter and the inverter are coupled to each otherand commonly use the switching elements Q11 and Q12.

More specifically, charges are accumulated in the first capacitor C11 bythe switching operation of the switching elements Q11 and Q21configuring the half-bridge circuit, such that a voltage across thefirst capacitor C11 becomes the boost voltage obtained by boosting theinput voltage provided by the input power source 300, and the magnitudeof the boost voltage is determined by the duty cycle of the controlsignals con11 and con21. In addition, the AC voltage generated by usingthe boost voltage accumulated in the output capacitor C11 is appliedacross the resonator 121 by the switching operation of the switchingelements Q11 and Q21 configuring the half-bridge circuit. The amplitudeof the AC voltage is determined by the magnitude of the boost voltage,and the frequency of the AC voltage is determined by the frequency ofthe control signals con11 and con21.

The switching operation of the switching elements Q11 and Q21 arecontrolled differently based on the modes of the wireless powertransmitter 1-1.

The second capacitor C21 and the second coil L21 are connected in seriesbetween the first node N1 and the ground terminal. The second capacitorC21 is the resonance capacitor, the second coil L21 is the resonancecoil, and an LC resonance is provided by the second capacitor C21 andthe second coil L21. Therefore, the resonance frequency f_r (FIG. 6) ofthe resonator 121 is determined by capacitance of the second capacitorC21 and inductance of the second coil L21. That is, the capacitance ofthe second capacitor C21 and the inductance of the second coil L21 aredetermined based on a general environment in which the wireless powertransmitter 1-1 is used, for example, a wireless power transmissionstandard. The frequency range of the control signals con11 and con21 isdetermined based on the resonance frequency in response to thedetermined capacitance and inductance.

The controller 201 outputs the control signals con11 and con21 inresponse to the request signal req. The controller 201 adjusts a dutycycle and/or a frequency of the control signals con11 and con21 inresponse to the request signal req.

FIG. 9 is a diagram schematically illustrating a configuration of awireless power transmitter 1-2 including a circuit unit 102 and acontroller 202, according to an embodiment. The circuit unit 102includes a converter 112 and a resonator 122. The converter 112 includesswitching elements Q12 and Q22, a first coil L12, a first capacitor C12,and a diode D, and the resonator 122 includes a second capacitor C22 anda second coil L22.

Functions of the circuit unit 102, the converter 112, the resonator 122,the controller 202, and the input power source 300 are substantially thesame as those of each of the circuit unit 100, the converter 110, theresonator 120, the controller 200, and the input power source 300,respectively, described in FIG. 7. In addition, the configuration andoperation of the resonator 122 are the same as those of the resonator121 described in FIG. 8.

The first coil L12 is connected between a terminal to which the inputvoltage is applied and the first node N1. The first switching elementQ12 is connected between the first node N1 and the second node N2. Thesecond switching element Q22 is connected between the first node N1 anda ground terminal. The first capacitor C12 is connected between thesecond node N2 and the ground terminal. The diode D is connected betweenthe second node N2 and the terminal to which the input voltage isapplied. The AC voltage generated by the converter 112 is output to thefirst node N1. The voltage of the second node N2 is a boost voltageobtained by boosting the input voltage by the converter 112. The firstswitching element Q12 is turned on and off in response to a firstcontrol signal con12, and the second switching element Q22 is turned onand off in response to a second control signal con22. In addition, thefirst switching element Q12 and the second switching element Q22 areturned on and off complementarily with each other.

An operation of the converter 112 can be easily understood withreference to the operation of the converter 111 described in FIG. 8. Inaddition, as illustrated in FIG. 9, the converter 112 includeshalf-bridge circuits Q12 and Q22 that perform both the functions of theboost converter and the inverter. That is, the converter 112 includesthe boost converter and the inverter, and the boost converter and theinverter share the switching elements Q12 and Q22.

Since the converter 112 includes the diode D for preventing a reversecurrent flowing to the terminal to which the input voltage is appliedfrom a boost node, it prevents ripples caused by the complementaryswitching operation of the first switching element Q12 and the secondswitching element Q22.

FIG. 10 is a diagram schematically illustrating a configuration of awireless power transmitter 1-3 including a circuit unit 103 and acontroller 203, according to an embodiment. The circuit unit 103includes a converter 113 and a resonator 123. The converter 113 includesswitching elements Q13 and Q23, a first coil L13 and a first capacitorC13. The resonator 123 includes a second capacitor C23 and a second coilL23.

Functions of the circuit unit 103, the converter 113, the resonator 123,the controller 203, and the input power source 300 are substantially thesame as those of the circuit unit 100, the converter 110, the resonator120, the controller 200, and the input power source 300, respectively,described in FIG. 7. In addition, the configuration and operation of theresonator 122 are the same as those of the resonator 121 described inFIG. 8.

The first coil L13 is connected between a terminal to which the inputvoltage is applied and the first node N1. The first switching elementQ13 is connected between the first node N1 and the second node N2. Thesecond switching element Q23 is connected between the first node N1 anda ground terminal. The first capacitor C13 is connected between thesecond node N2 and the terminal to which the input voltage is applied.The AC voltage generated by the converter 113 is output to the firstnode N1. The voltage of the second node N2 is a boost voltage obtainedby boosting the input voltage by the converter 113. The first switchingelement Q13 is turned on and off in response to a first control signalcon13, and the second switching element Q23 is turned on and off inresponse to a second control signal con23. In addition, the firstswitching element Q13 and the second switching element Q23 are turned onand off complementarily with each other.

An operation of the converter 113 can be easily understood withreference to the operation of the converter 111 described in FIG. 8. Inaddition, as illustrated in FIG. 10, the converter 113 includeshalf-bridge circuits Q13 and Q23 that perform both the functions of theboost converter and the inverter. That is, the converter 113 includesthe boost converter and the inverter, and the boost converter and theinverter share the switching elements Q13 and Q23.

The converter 113 improves initial operation performance by causing aninitial voltage of the first capacitor C13 to be the input voltage. Inaddition, the converter 113 prevents ripples which may be caused when aboosting is performed by an alternative operation of the switchingelements Q13 and Q23.

FIG. 11 is a diagram schematically illustrating a configuration of awireless power transmitter 1-4 including a circuit unit 104 and acontroller 204, according to an embodiment. The circuit unit 104includes a converter 114 and a resonator 124. The converter 114 includesswitching elements Q14, Q24, Q34, and Q44, a first coil L14, and a firstcapacitor C14. The resonator 124 includes a second capacitor C24 and asecond coil L24.

Functions of the circuit unit 104, the converter 114, the resonator 124,the controller 204, and the input power source 300 are substantially thesame as those of the circuit unit 100, the converter 110, the resonator120, the controller 200, and the input power source 300, respectively,described in FIG. 7. In addition, the configuration and operation of theresonator 122 are the same as those of the resonator 121 described inFIG. 8.

The first coil L14 is connected between a terminal to which the inputvoltage is applied and the first node N1. The first switching elementQ14 is connected between the first node N1 and the second node N2. Thesecond switching element Q24 is connected between the first node N1 anda ground terminal. The third switching element Q34 is connected betweenthe second node N2 and a third node N3. The fourth switching element Q44is connected between the third node N3 and a ground node. The firstcapacitor C14 is connected between the second node N2 and the groundnode. A voltage between the first node N1 and the third node N3 is theAC voltage generated by the converter 114. The voltage of the secondnode N2 is a boost voltage obtained by boosting the input voltage by theconverter 114. The first switching element Q14 is turned on and off inresponse to a first control signal con14. The second switching elementQ24 is turned on and off in response to a second control signal con24.The third switching element Q34 is turned on and off in response to athird control signal con34. The fourth switching element Q44 is turnedon and off in response to a fourth control signal con44. In addition,the first switching element Q14 and the second switching element Q24 areturned on and off complementarily with each other, and the thirdswitching element Q34 and the fourth switching element Q44 are turned onand off complementarily with each other. The third switching element Q34maintains an OFF state, or may be turned on and off at the same timingas the second switching element Q24, and the fourth switching elementQ44 maintains an ON state, or may be turned on and off at the sametiming as the first switching element Q14.

The resonator 124 is connected between the first node N1 and the thirdnode N3.

That is, the converter 114 is implemented as a full-bridge circuit. Insome cases, the third switching element Q34 maintains the OFF state andthe fourth switching element Q44 maintains the ON state, such that theconverter is operated in the same manner as the half-bridge circuit, andthe third switching element Q34 is turned on and off at the same timingas the second switching element Q24, and the fourth switching elementQ44 is turned on and off at the same timing as the first switchingelement Q14, such that the converter 114 is operated in the same manneras the full-bridge circuit. In some cases, the third switching elementQ34 and the fourth switching element Q44 are each turned on and off at atiming different from that of each of the second switching element Q24and the first switching element Q14, and the converter 114 is alsooperated as the full-bridge circuit.

In the embodiment illustrated in FIG. 11, the first coil L14, the firstcapacitor C14, the first switching element Q14, and the second switchingelement Q24 are operated as the boost converter, and the first switchingelement Q14, the second switching element Q24, the third switchingelement Q34, and the fourth switching element Q44 are operated as theinverter. That is, the first switching element Q14 and the secondswitching element Q24 are operated as the boost converter, and aresimultaneously operated as the inverter. In other words, the boostconverter and the inverter share the f

First switching element Q14 and the second switching element Q24 and arecoupled to each other.

An output voltage Vinv(t) of the converter 114 of the wireless powertransmitter 1-4 of FIG. 11, that is, a voltage between the first node N1and the third node N3, are determined by Equation 3.

Vinv(t)=4(Vin/(1−D))sin(wt/π)  [Equation 3]

In Equation 3, Vin is magnitude of a voltage of power input from theinput power source 300, D is a duty cycle of a control signal con24, andw is a frequency of control signals con14, con24, con34, and con44.

That is, according to the embodiment of FIG. 11, since the same effectas that of doubling the input voltage is obtained as compared to thehalf-bridge circuit, current stress of the coil is reduced, andefficiency is also improved.

FIG. 12 is a diagram schematically illustrating a configuration of awireless power transmitter 1-5 including a circuit unit 105 and acontroller 205, according to an embodiment. The circuit unit 105includes a converter 115 and a resonator 125. The converter 115 includesswitching elements Q15, Q25, Q35, and Q45, a first coil L15, a thirdcoil L35, and a first capacitor C15. The resonator 125 includes a secondcapacitor C25 and a second coil L25.

Functions of the circuit unit 105, the converter 115, the resonator 125,the controller 205, and the input power source 300 are substantially thesame as that of each of the circuit unit 100, the converter 110, theresonator 120, the controller 200, and the input power source 300,respectively, described in FIG. 7. In addition, the configuration andoperation of the resonator 125 are the same as those of the resonator121 described in FIG. 8.

The first coil L15 is connected between a terminal to which the inputvoltage is applied and the first node N1. The first switching elementQ15 is connected between the first node N1 and the second node N2. Thesecond switching element Q25 is connected between the first node N1 anda ground terminal. The third switching element Q35 is connected betweenthe second node N2 and a third node N3. The fourth switching element Q45is connected between the third node N3 and a ground node. The third coilL35 is connected between the terminal to which the input voltage isapplied and the third node N3. The first capacitor C15 is connectedbetween the second node N2 and the ground node. A voltage between thefirst node N1 and the third node N3 is the AC voltage generated by theconverter 115. The voltage of the second node N2 is a boost voltageobtained by boosting the input voltage by the converter 115. The firstswitching element Q15 is turned on and off in response to a firstcontrol signal con15. The second switching element Q25 is turned on andoff in response to a second control signal con25. The third switchingelement Q35 is turned on and off in response to a third control signalcon35. The fourth switching element Q45 is turned on and off in responseto a fourth control signal con45. In addition, the first switchingelement Q15 and the second switching element Q25 are turned on and offcomplementarily with each other, and the third switching element Q35 andthe fourth switching element Q45 are turned on and off complementarilywith each other. The third switching element Q35 maintains an OFF state,or may be turned on and off at the same timing as the second switchingelement Q25, and the fourth switching element Q45 maintains an ON state,or may be turned on and off at the same timing as the first switchingelement Q15.

The resonator 125 is connected between the first node N1 and the thirdnode N3.

That is, the converter 115 is implemented as a full-bridge circuit. Insome cases, the third switching element Q35 maintains the OFF state andthe fourth switching element Q45 maintains the ON state, such that theconverter is operated in the same manner as the half-bridge circuit, andthe third switching element Q35 is turned on and off at the same timingas the second switching element Q25, and the fourth switching elementQ45 is turned on and off at the same timing as the first switchingelement Q15, such that the converter 115 is operated in the same manneras the full-bridge circuit. In some cases, the third switching elementQ35 and the fourth switching element Q45 are each turned on and off at atiming different from that of each of the second switching element Q25and the first switching element Q15, and the converter 115 is alsooperated as the full-bridge circuit.

In the embodiment illustrated in FIG. 12, the first coil L15, the thirdcoil L25, the first capacitor L15, the first switching element C15, thesecond switching element Q25, the third switching element Q35, and thefourth switching element Q45 are operated as the boost converter, andthe first switching element Q15, the second switching element Q24, thethird switching element Q35, and the fourth switching element Q45 areoperated as the inverter. That is, the first switching element Q15, thesecond switching element Q24, the third switching element Q35, and thefourth switching element Q45 are operated as the boost converter, andsimultaneously operated as the inverter. In other words, the boostconverter and the inverter share the first switching element Q15, thesecond switching element Q24, the third switching element Q35, and thefourth switching element Q45, and are coupled to each other.

According to the embodiment of FIG. 12, since the converter is operatedas the full-bridge circuit to obtain the same effect as that of theinput voltage being doubled as compared to the half-bridge circuit,current stress of the coil is reduced and efficiency improved. Inaddition, since the third switching element Q35 and the fourth switchingelement Q45 also contribute to boosting the input voltage, a capacitorhaving lower capacitance may also be used as the first capacitor C15.

FIG. 13 is a diagram schematically illustrating a configuration of awireless power transmitter 1-6 including a circuit unit 106 and acontroller 206, according to an embodiment. The circuit unit 106includes a converter 116 and a resonator 126. The converter 116 includesswitching elements Q16, Q26, and Q56, a first coil L16, a firstcapacitor C16, and a diode D. The resonator 126 includes a secondcapacitor C26 and a second coil L26.

Functions of the circuit unit 106, the converter 116, the resonator 126,the controller 206, and the input power source 300 are substantially thesame as that of each of the circuit unit 101, the converter 111, theresonator 121, the controller 201, and the input power source 300,respectively, described in FIG. 8. In addition, the configuration andoperation of the resonator 126 are the same as those of the resonator121 described in FIG. 8.

The first coil L13 and a fifth switching element Q56 are connected inseries between a terminal to which the input voltage is applied and thefirst node N1. The switching element Q16 is connected between the firstnode N1 and the second node N2. The second switching element Q26 isconnected between the first node N1 and a ground terminal. The firstcapacitor C16 is connected between the second node N2 and the groundterminal. The diode D is connected between the second node N2 and theterminal to which the input voltage is applied. The AC voltage generatedby the converter 116 is output to the first node N1. The voltage of thesecond node N2 is a boost voltage obtained by boosting the input voltageby the converter 116. The first switching element Q16 is turned on andoff in response to a first control signal con16. The second switchingelement Q26 is turned on and off in response to a second control signalcon22. The fifth switching element Q56 is turned on and off in responseto a fifth control signal con56. In addition, the first switchingelement Q16 and the second switching element Q26 are turned on and offcomplementarily with each other.

An operation of the converter 116 can be easily understood withreference to the operation of the converter 111 described in FIG. 8. Inaddition, as illustrated in FIG. 13, the converter 116 includeshalf-bridge circuits Q16 and Q26 that perform both the functions of theboost converter and the inverter. That is, the converter 116 includesthe boost converter and the inverter, and the boost converter and theinverter share the switching elements Q16 and Q26.

The fifth switching element Q56 is turned on and off based on themagnitude of the input voltage input from the input power source 300.For example, when the magnitude of the input voltage is a referencevalue or less, the fifth switching element Q56 is turned on, and whenthe magnitude of the input voltage is greater than the reference value,the fifth switching element Q56 is turned off. When the fifth switchingelement Q56 is turned off, the converter 116 does not function as theboost converter, and functions only as the inverter.

Therefore, according to the embodiment of FIG. 13, since the function ofthe converter 116 is varied depending on the magnitude of the inputvoltage, the power is more efficiently transmitted.

Although not illustrated, the fifth switching element Q56 may also beadded to each of the embodiments of FIGS. 8, 10, 11, and 12. Inaddition, the diode D of FIG. 9 may also be added to the embodiments ofFIGS. 11 and 12. In addition, the first capacitor C14 and C15 accordingto the embodiments of FIGS. 11 and 12 may be connected in the samemanner as the first capacitor C13 according to the embodiment of FIG.10.

FIG. 14 is a diagram schematically illustrating a configuration of awireless power transmitter 1-7 including a circuit unit 107 and acontroller 207, according to an embodiment. The circuit unit 107includes a converter 117 and a resonator 127. The converter 117 includesswitching elements Q17, Q27, and Q67, a first coil L17, a firstcapacitor C17, a diode D, and a third capacitor C37. The resonator 127includes a second capacitor C27 and a second coil L27.

Functions of the circuit unit 107, the converter 117, the resonator 127,the controller 207, and the input power source 300 are substantially thesame as that of each of the circuit unit 100, the converter 110, theresonator 120, the controller 200, and the input power source 300,respectively, described in FIG. 7. In addition, the configuration andoperation of the resonator 127 are the same as those of the resonator121 described in FIG. 8.

The first coil L17 is connected between a terminal to which the inputvoltage is applied and the third node N3. The third capacitor C37 isconnected between the terminal to which the input voltage is applied anda ground terminal. The sixth switching element Q67 is connected betweenthe third node N3 and the ground terminal. The diode D is connectedbetween the third node N3 and the second node N2. The first capacitorC17 is connected between the second node N2 and the ground terminal. Thefirst switching element Q12 is connected between the first node N1 andthe second node N2. The second switching element Q22 is connectedbetween the first node N1 and the ground terminal. The AC voltagegenerated by the converter 117 is output to the first node N1. Thevoltage of the second node N2 is a boost voltage obtained by boostingthe input voltage by the converter 117. The first switching element Q17is turned on and off in response to a first control signal con17. Thesecond switching element Q27 is turned on and off in response to asecond control signal con27. The sixth switching element Q67 is turnedon and off in response to a fifth control signal con67. In addition, thefirst switching element Q17 and the second switching element Q27 areturned on and off complementarily with each other.

According to the embodiment of FIG. 14, the duty cycle of the firstswitching element Q17 and the second switching element Q27 is fixed.That is, the amount of power received by the wireless power receiver isadjusted by adjusting a duty cycle of the sixth switching element Q67,or adjusting an operating frequency of the first switching element Q17and the second switching element Q27.

In FIG. 14, the first coil L17, the sixth switching element Q67, thediode D, and the first capacitor C17 are operated as the boostconverter, and the first switching element Q17 and the second switchingelement Q27 are operated as the inverter. That is, the boost converterand the inverter of the converter 117 are similar to those illustratedin FIG. 14.

Although FIG. 14 illustrates the case in which the converter 117includes the half-bridge inverter, the converter 117 may also includethe boost converter and the full-bridge inverter.

FIG. 15 is a diagram schematically illustrating a configuration of awireless power transmitter according to an embodiment. The wirelesspower transmitter 1-8 includes a circuit unit 108 and a controller 208.The circuit unit 108 includes a converter 118 and a resonator 128. Theconverter 118 includes switching elements Q18, Q28, Q38, and Q48, and athird capacitor C38. The resonator 128 includes a second capacitor C28and a second coil L28. In FIG. 15, reference numeral 300 denotes aninput power source.

Functions of the circuit unit 108, the converter 118, the resonator 128,the controller 208, and the input power source 300 are substantially thesame as that of each of the circuit unit 100, the converter 110, theresonator 120, the controller 200, and the input power source 300described in FIG. 7. In addition, the configuration and operation of theresonator 128 are the same as those of the resonator 121 described inFIG. 8.

The first switching element Q18 is connected between the first node N1and the second node N2. The second switching element Q28 is connectedbetween the first node N1 and a ground terminal. The third switchingelement Q38 is connected between the second node N2 and the third nodeN3. The fourth switching element Q48 is connected between the third nodeN3 and a ground node. The third capacitor C38 is connected between thesecond node N2 and the ground node. A voltage between the first node N1and the third node N3 is the AC voltage generated by the converter 118.The input voltage output from the input power source 300 is applied tothe second node N2. The first switching element Q18 is turned on and offin response to a first control signal con18. The second switchingelement Q28 is turned on and off in response to a second control signalcon28. The third switching element Q38 is turned on and off in responseto a third control signal con38. The fourth switching element Q48 isturned on and off in response to a fourth control signal con48. Inaddition, the first switching element Q18 and the second switchingelement Q28 are turned on and off complementarily with each other, andthe third switching element Q38 and the fourth switching element Q48 areturned on and off complementarily with each other. The third switchingelement Q38 maintains an OFF state, or may be turned on and off at thesame timing as the second switching element Q28, and the fourthswitching element Q48 maintains an ON state, or may be turned on and offat the same timing as the first switching element Q18. In some cases,the third switching element Q38 and the fourth switching element Q48 areeach turned on and off at a timing different from that of each of thesecond switching element Q28 and the first switching element Q18.

The converter 118 includes only the inverter similar to that illustratedin FIG. 15. Although FIG. 15 illustrates the case in which the converter118 includes the full-bridge inverter, the converter 118 may alsoinclude the half-bridge inverter.

The wireless power transmitters 1 through 1-8 illustrated in FIGS. 7through 15 are operated in a detection mode and a power transmissionmode. The power transmission mode includes two or more of the normalmode, the boost mode, and the reduction mode.

The detection mode, which is a mode for determining whether an externalobject is approaching the wireless power transmitter or whether theapproaching external object is the wireless power receiver, correspondsto the analog ping phase and the digital ping phase described above.

In the detection mode, the wireless power transmitter transmits ananalog ping signal for determining whether the external object isapproaching and a digital ping signal for determining whether theapproaching object is the wireless power receiver. In this case, asdescribed above, after the wireless power transmitter periodicallytransmits the analog ping signal, the wireless power transmitter 1, 1-1,1-2, 1-3, 1-4, 1-5, 1-6, 1-7, or 1-8 transmits the digital ping signalwhen it is determined that the external object is approaching, ortransmits the digital ping signal based on a set period.

Hereinafter, for convenience of explanation, the analog ping signal andthe digital ping signal transmitted by the wireless power transmitter 1,1-1, 1-2, 1-3, 1-4, 1-5, 1-6, 1-7, or 1-8 in the detection mode arecollectively referred to as a ping signal.

The detection mode includes, for example, a first mode and a secondmode. The first mode corresponds to an initial operation mode startingan operation to transmit the ping signal after a stop state for areference time or longer, such as a case in which turned-off power ofthe wireless power transmitter is switched to an ON state. The secondmode corresponds to a standby operation mode for transmitting the pingsignal in the stop state for less than the reference time, after theinitial operation mode.

In the initial operation mode, the converter 111, 112, 113, 114, 115,116, or 117 (FIGS. 8 through 14) gradually boosts the input voltage, andstores boost power in the first capacitor C11, C12, C13, C14, C15, C16,or C17 (FIGS. 8 through 14). The converter 111, 112, 113, 114, 115, 116,or 117 eliminates a problem in which a predetermined ripple is caused inthe boost power generated by the alternative switching by graduallyboosting the input voltage.

The input voltage is gradually boosted by gradually increasing a dutycycle of a gate signal provided to the switching element Q21, Q22, Q23,Q24, Q25 (and/or Q45), Q26, or Q67 (FIGS. 8 through 14) of the converter111, 112, 113, 114, 115, 116, or 117 from a first duty cycle. It can beunderstood that the gradual increase of the duty cycle means that theduty cycle is repeatedly and sequentially increased from the specificduty cycle by a reference duty cycle.

As an example, a first duty cycle corresponds to a duty cycle increasedfrom a duty cycle of 0% by the reference duty cycle. According to anembodiment, the first duty cycle is set as the duty cycle close to 0% toprevent the rapid boosting of the input power in a phase in which anoperation starts, after the stop state for the reference time or more,whereby the problem in which the predetermined ripple is caused in theboost power is effectively eliminated.

In an operation of boosting the input voltage by sequentially increasingthe duty cycle from the first duty cycle close to the duty cycle of 0%by the reference duty cycle, the converter (or the controller)calculates data regarding a voltage level of the boost power which isgradually boosted and a duty cycle corresponding to the voltage level.The data regarding the voltage level of the boost power which isgradually boosted and the duty cycle corresponding to the voltage levelcalculated by the converter 111, 112, 113, 114, 115, 116, or 117 (or thecontroller 201, 202, 203, 204, 205, 206, 207, or 208 (FIGS. 8 through14)) may be stored in a separate memory element.

In addition, when the voltage level of the boost power stored in thefirst capacitor C11, C12, C13, C14, C15, C16, or C17 (FIGS. 8 through14) reaches a voltage level of target boost power, the converter 111,112, 113, 114, 115, 116, or 117 outputs an AC voltage (or an alternatingcurrent) to transmit a ping signal through the resonator 121, 122, 123,124, 125, 126, or 127 (FIGS. 8 through 14).

Even in a case in which various voltage levels are provided by the inputpower source 300, the converter 111, 112, 113, 114, 115, 116, or 117boosts the input voltage up to the target boost voltage. Therefore, evenin a case in which the voltage level of the input voltage is varied, theconverter 111, 112, 113, 114, 115, 116, or 117 boosts the input voltageup to a set target boost voltage to decrease dependency on the inputpower source 300.

FIG. 16 is an operation flowchart illustrating an operation in aninitial operation mode of the wireless power transmitter 1, 1-1, 1-2,1-3, 1-4, 1-5, 1-6, 1-7, or 1-8 and the wireless power transmissionmethod, according to an embodiment.

Referring to FIG. 16, in the initial operation mode, the controller 201,202, 203, 204, 205, 206, 207, or 208 determines whether a current dutycycle is a duty cycle of 0% in operation S1110. If it is determined thatthe current set duty cycle is 0%, the duty cycle is set as the firstduty cycle which is increased from the duty cycle of 0% by the referenceduty cycle in operation S1120. If it is determined that the current setduty cycle is not 0%, the boost power and the target boost power arecompared with each other in operation S1130 and, if it is determined,based on the comparison between the boost power and the target boostpower, that the boost power does not reach the target boost power, theduty cycle is increased by the reference duty cycle in operation S1140to gradually boost the boost power. On the other hand, if it isdetermined, based on the comparison between the boost power and thetarget boost power, that the boost power reaches the target boost power,the current duty cycle and a limit duty cycle are compared with eachother in operation S1150. The limit duty cycle corresponds to a maximumduty cycle which is allowed in the detection mode. By setting the limitduty cycle in the detection mode, excessive power consumption fortransmission of the ping signal is prevented and over-heating iseliminated. If it is determined, based on the comparison between thecurrent duty cycle and the limit duty cycle, that the current duty cycleis higher than the limit duty cycle, the limit duty cycle is stored as aping duty cycle corresponding to the target boost power in operationS1160, and, if the current duty cycle is lower than the limit dutycycle, the current duty cycle is stored as the ping duty cyclecorresponding to the target boost power in operation S1170. Thereafter,the ping signal is transmitted using the target boost power in operationS1180, and the initial operation mode ends. Thereafter, after theinitial operation mode ends, the wireless power transmitter 1, 1-1, 1-2,1-3, 1-4, 1-5, 1-6, 1-7, or 1-8 enters the standby operation mode, orenters a power transmission mode based on a response signal of thewireless power receiver 2 (FIG. 1) for the ping signal transmitted inthe initial operation mode.

In the standby operation mode, the converter 111, 112, 113, 114, 115,116, or 117 (or the controller 201, 202, 203, 204, 205, 206, 207, or208) gradually increases the duty cycle from a second duty cycle toboost the input voltage. The converter gradually increases the dutycycle from the second duty cycle to significantly decrease an inrushcurrent caused by a rapid voltage change, thereby decreasing standbypower. In addition, the converter 111, 112, 113, 114, 115, 116, or 117prevents a peak current from being input to the resonator to reducenoise of the wireless power transmitter.

The second duty cycle is determined based on a voltage level of thecurrent boost power.

In the standby operation mode, the boost power stored in the firstcapacitor C11, C12, C13, C14, C15, C16, or C17 (each of FIGS. 8 through14) is discharged based on a period in which the ping signal istransmitted, such that the voltage level of the boost power is graduallydecreased. The second duty cycle is determined by considering an amountby which the boost power stored in the first capacitor C11, C12, C13,C14, C15, C16, or C17 is discharged based on a time interval at whichthe ping signal is transmitted. The second duty cycle is higher than thefirst duty cycle.

As an example, the voltage level of the boost power stored in the firstcapacitor C11, C12, C13, C14, C15, C16, or C17 is directly detected by aseparate detection element. A duty cycle corresponding to the detectedvoltage level of the boost power may be determined as the second dutycycle.

In another example, the voltage level of the boost power is estimatedbased on the period in which the ping signal is transmitted.Specifically, since the voltage level of the boost power is decreasedbased on the discharge by the time interval at which the ping signal istransmitted, when the period of the ping signal is determined, thevoltage level of the boost power in which the voltage level is partiallydecreased from the target boost power is estimated. A duty cyclecorresponding to the estimated voltage level of the boost power isdetermined as the second duty cycle.

As described above, the data regarding the voltage level of the boostpower which is gradually boosted and the duty cycle corresponding to thevoltage level calculated by the converter 111, 112, 113, 114, 115, 116,or 117 (or the controller 201, 202, 203, 204, 205, 206, 207, or 208) ofthe initial operation mode may be stored in a separate memory element.In this case, the second duty cycle is determined based on the dataregarding the voltage level of the boost power stored in the initialoperation mode and the duty cycle corresponding to the voltage level ofthe boost power.

According to an embodiment, a weighting index is calculated by comparingthe voltage level of the target boost power with the voltage level ofthe current boost power, and the second duty cycle is calculated byapplying the calculated weighting index to a ping duty cyclecorresponding to the target boost power. In this case, the weightingindex has a value greater than 0 but less than 1. This embodiment isapplied to a case in which only the voltage level of the target boostpower and the ping duty cycle corresponding to the voltage level of thetarget boost power are stored in the data stored in the initialoperation mode. In the initial operation mode, all voltage levels of theboost power and a plurality of ping duties corresponding thereto are notstored. That is, only the voltage level of the target boost power andthe ping duty cycle corresponding thereto are stored, whereby a size ofthe memory element may be reduced.

According to another embodiment, the second duty cycle is determined bya retrieval of a duty cycle corresponding to the voltage level of thecurrent boost power. This embodiment is applied to a case in which allvoltage levels of the boost power and ping duties corresponding theretoare stored in the initial operation mode. In this case, all voltagelevels of the boost power and the ping duties corresponding thereto arestored in a form of a lookup table in the data, and a load of thecalculation operation is removed using the lookup table in the standbyoperation mode.

The converter 111, 112, 113, 114, 115, 116, or 117 (or the controller201, 202, 203, 204, 205, 206, 207, or 208) gradually increases the dutycycle from the second duty cycle to gradually boost the input voltage.In a case in which the duty cycle is gradually increased and reaches theping duty cycle, since the voltage level of the boost power stored inthe first capacitor reaches the voltage level of the target boost power,the converter 111, 112, 113, 114, 115, 116, or 117 outputs the ACcurrent to transmit the ping signal through the resonator 121, 122, 123,124, 125, 126, or 127.

FIG. 17 is an operation flowchart illustrating an operation in a standbyoperation mode of the wireless power transmitter 1, 1-1, 1-2, 1-3, 1-4,1-5, 1-6, 1-7, or 1-8 and the wireless power transmission method,according to an embodiment.

Referring to FIG. 17, in the standby operation mode, the controller 201,202, 203, 204, 205, 206, 207, or 208 determines whether a current dutycycle is a duty cycle of 0% in operation S1210. If it is determined thatthe current set duty cycle is 0%, the duty cycle is set as the secondduty cycle in operation S1220. The second duty cycle is higher than thefirst duty cycle, and as an example, the second duty cycle is calculatedby applying a weighting index to a ping duty cycle. In this case, theweighting index is a value greater than 0 but less than 1.

If it is determined in operation S1210 that the current set duty cycleis not 0%, the current duty cycle and the ping duty cycle which iscalculated and stored in the initial operation mode are compared witheach other in operation S1230. If it is determined, as a result of thecomparison between the current duty cycle and the ping duty cycle, thatthe current duty cycle is lower than the ping duty cycle, the duty cycleis increased by a reference duty cycle in operation S1240 to graduallyboost the boost power. Alternatively, if it is determined in operationS1230 that the current duty cycle is higher than the ping duty cycle,the duty cycle is limited to the ping duty cycle in operation S1250, theping signal is transmitted in operation S1260, and the standby operationmode ends. Thereafter, the wireless power transmitter 1, 1-1, 1-2, 1-3,1-4, 1-5, 1-6, 1-7, or 1-8 enters the power transmission mode based onthe response signal of the wireless power receiver 2 for the pingsignal.

FIG. 18 is a diagram illustrating a change of a boost voltage in theinitial operation mode and the standby operation mode of the wirelesspower transmitter 1, 1-1, 1-2, 1-3, 1-4, 1-5, 1-6, 1-7, or 1-8 and thewireless power transmission method.

Referring to FIG. 18, in the initial operation mode, the converter 110,111, 112, 113, 114, 115, 116, 117, or 118 (FIGS. 7 through 15) (or thecontroller 200, 201, 202, 203, 204, 205, 206, 207, or 208 (FIGS. 7through 15)) gradually increases the duty cycle from the first dutycycle to gradually boost the input voltage. As a result of the boostingof the converter 110, 111, 112, 113, 114, 115, 116, 117, or 118, whenthe boost power stored in the first capacitor C11, C12, C13, C14, C15,C16, or C17 (FIGS. 8 through 14) reaches the target boost power, theping signal is transmitted at a timing t1. After the ping signal istransmitted, the initial operation mode ends and the wireless powertransmitter 1, 1-1, 1-2, 1-3, 1-4, 1-5, 1-6, 1-7, or 1-8 enters thestandby operation mode.

In the standby operation mode, the voltage level of the boost powerstored in the first capacitor C11, C12, C13, C14, C15, C16, or C17 isdecreased based on the period in which the ping signal is transmitted.The converter 110, 111, 112, 113, 114, 115, 116, 117, or 118 (or thecontroller 200, 201, 202, 203, 204, 205, 206, 207, or 208) graduallyincreases the duty cycle from the second duty cycle at a timing t2 basedon the voltage level of the boost power stored in the first capacitor toboost the input voltage, and transmits the ping signal at a timing t3when the boost power stored in the first capacitor reaches the targetboost power as a result of the boosting of the converter. In this case,the above-mentioned operation is repeated based on a transmission periodof the ping signal, which is a time interval of a timing t3 to t5, or atime interval of a timing t5 to a timing t7. Thereafter, the wirelesspower transmitter 1, 1-1, 1-2, 1-3, 1-4, 1-5, 1-6, 1-7, or 1-8 entersthe power transmission mode based on the response signal of the wirelesspower receiver 2 for the ping signal.

Next, the power transmission mode will be described. Hereinafter, anoperation in the power transmission mode is performed by the controller200, 201, 202, 203, 204, 205, 206, 207, or 208 (of FIGS. 7 through 15).

FIG. 19 is a waveform diagram illustrating an operation of the wirelesspower transmitter 1, 1-1, 1-2, 1-3, 1-4, 1-5, 1-6, 1-7, or 1-8 and thewireless transmission method when an amount of power received by thewireless power receiver 2 is increased in a power transmission mode,based on an embodiment. The waveform diagram of FIG. 19 represents awaveform of a control signal for controlling switching elements of thewireless power transmitter 1, 1-1, 1-2, 1-3, 1-4, 1-5, 1-6, 1-7, or 1-8.

The first control signals con11, con12, con13, and con16 of FIGS. 8through 10 and 13 are equivalent to the first control signal con1 ofFIG. 19, and the second control signals con21, con22, con23, and con26of FIGS. 8 through 10 and 13 are equivalent to the second control signalcon2 of FIG. 19.

In addition, the first control signal con14, con15, and con18 of FIGS.11, 12, and 15 are equivalent to the first control signal con1 of FIG.19. The second control signals con24, con25, and con28 of FIGS. 11, 12,and 15 are equivalent to the second control signal con2 of FIG. 19. Inthis case, the third control signals con34, con35, and con38 of FIGS.11, 12, and 15 are maintained at a low level. The fourth control signalscon44, con45, and con48 of FIGS. 11, 12, and 15 are maintained at a highlevel.

The control signals, initially output in the normal mode, have formssuch as those illustrated in (a) and (b) of FIG. 19. In this case, afrequency and a duty cycle of the control signals are the ping frequencyand the ping duty cycle described above. The control signals illustratedin (a) and (b) are also output in the detection mode.

In the normal mode, the frequency of the control signal is adjustedbased on the signal received from the wireless power receiver 2. Thatis, in a case in which an amount of power received by the wireless powerreceiver 2 is less than an amount of power required by the wirelesspower receiver 2, in the normal mode, the controller 200, 201, 202, 203,204, 205, 206, 207, or 208 decreases the frequency of the controlsignals con1 and con2 as illustrated in (c) and (d) of FIG. 19.Therefore, the amount of power received by the wireless power receiver 2is increased. The frequency of the control signals con1 and con2 of (c)and (d) may be a minimum value f1 (FIG. 6) of the frequency in thenormal mode. In the normal mode, the duty cycle is fixed to theabove-mentioned ping duty cycle.

In the boost mode, the duty cycle of the control signal is adjustedbased on the signal received from the wireless power receiver 2. Thatis, when the amount of power required by the wireless power receiver isnot received, even though the frequency of the control signals con1 andcon2 is decreased up to a predetermined reference frequency (e.g., f1 ofFIG. 6), as illustrated in (e) and (f) of FIG. 19, the controller 200,201, 202, 203, 204, 205, 206, 207, or 208 fixes the frequency of thecontrol signals con1 and con2 to the reference frequency (e.g., f1 ofFIG. 6), and increases the duty cycle of the second control signal con2.

Alternatively, as illustrated in (g) and (h) of FIG. 19, in the boostmode, the controller 200, 201, 202, 203, 204, 205, 206, 207, or 208additionally decreases the frequency of the control signals con1 andcon2. In this case, the duty cycle is fixed to the duty cycle which waspreviously increased.

FIG. 20 is a diagram illustrating an operation of the wireless powertransmitter 1, 1-1, 1-2, 1-3, 1-4, 1-5, 1-6, 1-7, or 1-8 and thewireless power transmission method when an amount of power received bythe wireless power receiver 2 is increased in a power transmission mode,according to an embodiment. The waveform diagram of FIG. 20 represents awaveform of a control signal for controlling switching elements of thewireless power transmitter 1-1, 1-2, 1-3, 1-4, 1-5, 1-6, 1-7, or 1-8.

The first control signals con14, con15, and con18 of FIGS. 11, 12, and15 are equivalent to the first control signal con1 of FIG. 20. Thesecond control signals con24, con25, and con28 of FIGS. 11, 12, and 15are equivalent to the second control signal con2 of FIG. 20. The thirdcontrol signals con34, con35, and con38 of FIGS. 11, 12, and 15 areequivalent to the third control signal con3 of FIG. 20. The fourthcontrol signals con44, con45, and con48 of FIGS. 11, 12, and 15 areequivalent to the fourth control signal con4 of FIG. 20.

FIG. 20 is similar to FIG. 19, except that FIG. 20 relates to the casein which the s 114, 115, and 118 (FIGS. 11, 12, and 15) are operated asthe full-bridge circuit.

The controller 200, 201, 202, 203, 204, 205, 206, 207, or 208 outputsthe control signals illustrated in (a) and (b). As described above, inthe normal mode, the controller 200, 201, 202, 203, 204, 205, 206, 207,or 208 also outputs the control signals initially output in the formsillustrated in (a) and (b) of FIG. 20, and also outputs the controlsignals in the detection mode. The duty cycle of the control signalscon1 and con4 illustrated in (a) is the above-mentioned ping duty cycle,and the frequency of the control signals con1, con2, con3, and con4illustrated in (a) and (b) is the above-mentioned ping frequency.

In the normal mode, in a case in which an amount of power received bythe wireless power receiver 2 is less than an amount of power requiredby the wireless power receiver 2, the controller 200, 201, 202, 203,204, 205, 206, 207, or 208 decreases the frequency of the controlsignals con1, con2, con3, and con4 as illustrated in (c) and (d) of FIG.20.

In the boost mode, the duty cycle of the control signal is adjustedbased on the signal received from the wireless power receiver 2. Thatis, when the amount of power required by the wireless power receiver 2is not received even though the frequency of the control signals con1,con2, con3, and con4 is decreased up to a predetermined frequency (e.g.,f1 of FIG. 6), as illustrated in (e) and (f) of FIG. 20, the controller200, 201, 202, 203, 204, 205, 206, 207, or 208 fixes the frequency ofthe control signals con1, con2, con3, and con4 to the referencefrequency (e.g., f1 of FIG. 6), and increases the duty cycle of thesecond control signal con2 and the third control signal con3.

Alternatively, as illustrated in (g) and (h) of FIG. 20, in the boostmode, the controller 200, 201, 202, 203, 204, 205, 206, 207, or 208additionally decreases the frequency of the control signals con1, con2,con3, and con5. In this case, the duty cycle is fixed to the duty cyclewhich is previously increased.

Although not illustrated in FIGS. 19 and 20, in the boost mode, thecontroller 200, 201, 202, 203, 204, 205, 206, 207, or 208 may alsoadditionally increase the duty cycle after additionally decreasing thefrequency as illustrated in (g) and (h).

FIG. 21 is a waveform diagram illustrating an operation of the wirelesspower transmitter 1-1, 1-2, 1-3, 1-4, 1-5, 1-6, 1-7, or 1-8 and thewireless power transmission method when an amount of power received bythe wireless power receiver 2 is decreased in a power transmission mode,according to an embodiment. The waveform diagram of FIG. 21 represents awaveform of a control signal for controlling switching elements of thewireless power transmitter 1-1, 1-2, 1-3, 1-4, 1-5, 1-6, 1-7, or 1-8.

The first control signals con11, con12, con13, and con16 of FIGS. 8through 10, and 13 are equivalent to the first control signal con1 ofFIG. 21, and the second control signals con21, con22, con23, and con26of FIGS. 8 through 10, and 13 are equivalent to the second controlsignal con2 of FIG. 21.

In addition, the first control signals con14, con15, and con18 of FIGS.11, 12, and 15 are equivalent to the first control signal con1 of FIG.21, and the second control signals con24, con25, and con28 of FIGS. 11,12, and 15 are equivalent to the second control signal con2 of FIG. 21.In this case, the third control signals con34, con35, and con38 of FIGS.11, 12, and 15 are maintained at a low level, and the fourth controlsignal con44, con45, and con48 of FIGS. 11, 12, and 15 are maintained ata high level.

First, the controller 200, 201, 202, 203, 204, 205, 206, 207, or 208outputs the same control signals con1 and con2 as those illustrated in(a) and (b) of FIG. 21. The controller 200, 201, 202, 203, 204, 205,206, 207, or 208 also outputs the control signals initially output inthe forms illustrated in (a) and (b) in the normal mode, and alsooutputs the same control signals as those illustrated in (a) and (b) inthe detection mode.

In a case in which an amount of power received by the wireless powerreceiver 2 is greater than an amount of power required by the wirelesspower receiver 2, in the normal mode, the controller 200, 201, 202, 203,204, 205, 206, 207, or 208 increases the frequency of the controlsignals con1 and con2 as illustrated in (c) and (d). Therefore, theamount of power received by the wireless power receiver 2 decreases. Thefrequency of the control signals con1 and con2 of (c) and (d) of FIG. 21is a maximum value f2 (FIG. 6) of the frequency in the normal mode. Inthe normal mode, the duty cycle is fixed to the above-mentioned pingduty cycle.

In the reduction mode, the duty cycle of the control signal is adjustedbased on the signal received from the wireless power receiver. That is,when the amount of power received by the wireless power receiver 2 isgreater than the amount of power required by the wireless power receiver2, even though the frequency of the control signals con1 and con2 isincreased up to a predetermined reference frequency (e.g., f2 of FIG.6), as illustrated in (e) and (f) of FIG. 21, the controller 200, 201,202, 203, 204, 205, 206, 207, or 208 fixes the frequency of the controlsignals con1 and con2 to the reference frequency (e.g., f2 of FIG. 6),and decreases the duty cycle of the second control signal con2.

Alternatively, as illustrated in (g) and (h) of FIG. 21, in thereduction mode, the controller 200, 201, 202, 203, 204, 205, 206, 207,or 208 also increases the frequency of the control signals con1 andcon2. In this case, the duty cycle may be fixed to the duty cycle whichis previously decreased.

FIG. 22 is a waveform diagram illustrating an operation of the wirelesspower transmitter 1, 1-2, 1-3, 1-4, 1-5, 1-6, 1-7, or 1-8 and thewireless power transmission method when an amount of power received bythe wireless power receiver 2 is decreased in a power transmission mode,according to an embodiment. The waveform diagram of FIG. 22 represents awaveform of a control signal for controlling switching elements of thewireless power transmitter 1, 1-2, 1-3, 1-4, 1-5, 1-6, 1-7, or 1-8.

The first control signals con14, con15, and con18 of FIGS. 11, 12, and15 are equivalent to the first control signal con1 of FIG. 22. Thesecond control signals con24, con25, and con28 of FIGS. 11, 12, and 15are equivalent to the second control signal con2 of FIG. 22. The thirdcontrol signals con34, con35, and con38 of FIGS. 11, 12, and 15 areequivalent to the third control signal con1 of FIG. 22. The fourthcontrol signals con44, con45, and con48 of FIGS. 11, 12, and 15 areequivalent to the fourth control signal con4 of FIG. 22.

FIG. 22 is similar to FIG. 21 except that FIG. 22 relates to the case inwhich the converter 114, 115, and 118 (FIGS. 11, 12, and 15) is operatedas the full-bridge circuit.

First, the controller 200, 201, 202, 203, 204, 205, 206, 207, or 208outputs the same control signals con1, con2, con3, and con4 as thoseillustrated in (a) and (b) of FIG. 22. The controller 200, 201, 202,203, 204, 205, 206, 207, or 208 also outputs the control signalsinitially output in the forms illustrated in (a) and (b) in the normalmode, and also outputs the same control signals as those illustrated in(a) and (b) in the detection mode.

In a case in which an amount of power received by the wireless powerreceiver 2 is greater than an amount of power required by the wirelesspower receiver 2, in the normal mode, the controller 200, 201, 202, 203,204, 205, 206, 207, or 208 increases the frequency of the controlsignals con1, con2, con3, and con4 as illustrated in (c) and (d) of FIG.22. Therefore, the amount of power received by the wireless powerreceiver 2 decreases. The frequency of the control signals con1, con2,con3, and con4 of (c) and (d) is a maximum value f2 (FIG. 6) of thefrequency in the normal mode. In the normal mode, the duty cycle isfixed to the above-mentioned ping duty cycle.

In the reduction mode, the duty cycle of the control signal is adjustedbased on the signal received from the wireless power receiver 2. Thatis, when the amount of power received by the wireless power receiver 2is greater than the amount of power required by the wireless powerreceiver 2 even though the frequency of the control signals con1, con2,con3, and con4 is increased up to a predetermined reference frequency(e.g., f2 of FIG. 6), as illustrated in (e) and (f) of FIG. 22, thecontroller 200, 201, 202, 203, 204, 205, 206, 207, or 208 fixes thefrequency of the control signals con1, con2, con3, and con4 to thereference frequency (e.g., f2 of FIG. 6), and decreases the duty cycleof the second control signal con2 and the third control signal con2 andcon3.

Alternatively, as illustrated in (g) and (h) of FIG. 22, in thereduction mode, the controller 200, 201, 202, 203, 204, 205, 206, 207,or 208 also increases the frequency of the control signals con1, con2,con3, and con4. In this case, the duty cycle is fixed to the duty cyclewhich is previously decreased.

FIG. 23 is a waveform diagram illustrating an operation of the wirelesspower transmitter 1, 1-2, 1-3, 1-4, 1-5, 1-6, 1-7, or 1-8 and thewireless power transmission method when an amount of power received bythe wireless power receiver 2 is decreased in a power transmission mode,according to an embodiment. The waveform diagram of FIG. 23 represents awaveform of a control signal for controlling switching elements of thewireless power transmitter 1, 1-2, 1-3, 1-4, 1-5, 1-6, 1-7, or 1-8.

The first control signals con14, con15, and con18 of FIGS. 11, 12, and15 are equivalent to the first control signal con1 of FIG. 23. Thesecond control signals con24, con25, and con28 of FIGS. 11, 12, and 15are equivalent to the second control signal con2 of FIG. 23. The thirdcontrol signals con34, con35, and con38 of FIGS. 11, 12, and 15 areequivalent to the third control signal con3 of FIG. 23. The fourthcontrol signals con44, con45, and con48 of FIGS. 11, 12, and 15 areequivalent to the fourth control signal con4 of FIG. 23.

First, the controller 200, 201, 202, 203, 204, 205, 206, 207, or 208outputs the same control signals con1, con2, con3, and con4 as thoseillustrated in (a) and (b) of FIG. 23. The controller 200, 201, 202,203, 204, 205, 206, 207, or 208 also outputs the control signalsinitially output in the forms illustrated in (a) and (b) in the normalmode, and also outputs the same control signals as those illustrated in(a) and (b) in the detection mode.

In a case in which an amount of power received by the wireless powerreceiver 2 is greater than an amount of power required by the wirelesspower receiver 2, in the normal mode, the controller 200, 201, 202, 203,204, 205, 206, 207, or 208 increases the frequency of the controlsignals con1, con2, con3, and con4 as illustrated in (c) and (d) of FIG.23. Therefore, the amount of power received by the wireless powerreceiver 2 decreases. The frequency of the control signals con1, con2,con3, and con4 of (c) and (d) is a maximum value f2 (FIG. 6) of thefrequency in the normal mode. In the normal mode, the duty cycle isfixed to the above-mentioned ping duty cycle.

In the reduction mode, the duty cycle of the control signal is adjustedbased on the signal received from the wireless power receiver 2. Thatis, when the amount of power received by the wireless power receiver 2is greater than the amount of power required by the wireless powerreceiver 2 even though the frequency of the control signals con1, con2,con3, and con4 is increased up to a predetermined reference frequency(e.g., f2 of FIG. 6), as illustrated in (e), (f), (g), and (h) of FIG.23, the controller 200, 201, 202, 203, 204, 205, 206, 207, or 208 fixesthe frequency of the control signals con1, con2, con3, and con4 to thereference frequency (e.g., f2 of FIG. 6), fixes the duty cycle of thesecond control signal con2, and decreases the duty cycle of the fourthcontrol signal con4. In this case, a dead time is increased in thefull-bridge circuit, and consequently, the amount of power transmittedby the wireless power transmitter 1, 1-2, 1-3, 1-4, 1-5, 1-6, 1-7, or1-8 is decreased, whereby the amount of power received by the wirelesspower receiver 2 is also decreased.

Alternatively, as illustrated in (i) and (j) of FIG. 23, in thereduction mode, the controller 200, 201, 202, 203, 204, 205, 206, 207,or 208 also increases the frequency of the control signals con1, con2,con3, and con4. In this case, the duty cycle of the control signals con1and con2 of (e) and (f) is equal to the duty cycle of the controlsignals con1 and con2 of (i) and (j). In addition, at the same time, asillustrated in (k) and (l) of FIG. 23, the third control signal con3maintains a low level, and the fourth control signal con4 maintains ahigh level. In this case, the converter 114, 115, or 118 of FIG. 11, 12or 15 is operated as the half-bridge circuit, such that the amount ofpower transmitted by the wireless power transmitter 2 is decreased,whereby the amount of power received by the wireless power receiver 2 isfurther decreased as compared to the case in which only the frequency isadjusted.

Although (k) and (l) of FIG. 23 illustrate the cases in which thecontroller 200, 201, 202, 203, 204, 205, 206, 207, or 208 fixesmaintains the third control signal con3 at the low level, and maintainsthe fourth control signal con4 at the high level, the third controlsignal con3 is equal to the second control signal con2 of (j), and thefourth control signal con4 is also equal to the first control signalcon1 of (i). That is, by increasing the frequencies of all of the firstto fourth control signals, the power received by the wireless powerreceiver 2 is reduced.

FIG. 24 is a waveform diagram illustrating an operation of the wirelesspower transmitter 1, 1-2, 1-3, 1-4, 1-5, 1-6, 1-7, or 1-8 and thewireless power transmission method when an amount of power received bythe wireless power receiver 2 is decreased in a power transmission mode,according to an embodiment. The waveform diagram of FIG. 24 represents awaveform of a control signal for controlling switching elements of thewireless power transmitter 1, 1-2, 1-3, 1-4, 1-5, 1-6, 1-7, or 1-8 . . ..

The first control signals con14, con15, and con18 of FIGS. 11, 12, and15 are equivalent to the first control signal con1 of FIG. 24. Thesecond control signals con24, con25, and con28 of FIGS. 11, 12, and 15are equivalent to the second control signal con2 of FIG. 24. The thirdcontrol signals con34, con35, and con38 of FIGS. 11, 12, and 15 areequivalent to the third control signal con3 of FIG. 24. The fourthcontrol signals con44, con45, and con48 of FIGS. 11, 12, and 15 areequivalent to the fourth control signal con4 of FIG. 24.

First, the controller 200, 201, 202, 203, 204, 205, 206, 207, or 208outputs the same control signals con1, con2, con3, and con4 as thoseillustrated in (a) and (b) of FIG. 24. The controller 200, 201, 202,203, 204, 205, 206, 207, or 208 also outputs the control signalsinitially output in the forms illustrated in (a) and (b) in the normalmode, and also outputs the same control signals as those illustrated in(a) and (b) in the detection mode.

In a case in which an amount of power received by the wireless powerreceiver 2 is greater than an amount of power required by the wirelesspower receiver 2, in the normal mode, the controller 200, 201, 202, 203,204, 205, 206, 207, or 208 increases the frequency of the controlsignals con1, con2, con3, and con4 as illustrated in (c) and (d) of FIG.24. Therefore, the amount of power received by the wireless powerreceiver 2 decreases. The frequency of the control signals con1, con2,con3, and con4 of (c) and (d) is a maximum value f2 (FIG. 6) of thefrequency in the normal mode. In the normal mode, the duty cycle isfixed to the above-mentioned ping duty cycle.

In a case in which an amount of power received by the wireless powerreceiver 2 is greater than an amount of power required by the wirelesspower receiver 2 even though the frequency of the control signals con1,con2, con3, and con4 is increased up to a predetermined referencefrequency (e.g., f2 of FIG. 6), the controller 200, 201, 202, 203, 204,205, 206, 207, or 208 is operated in the reduction mode. In thereduction mode, as illustrated in (e), (f), (g), and (h) of FIG. 24, thecontroller 200, 201, 202, 203, 204, 205, 206, 207, or 208 increases thefrequency of the first control signal con1 and the second control signalcon2, while the third control signal con3 maintains a low level and thefourth control signal con4 maintains a high level. In this case, theconverters 114, 115, and 118 of FIGS. 11, 12 and/or 15 are operated asthe half-bridge circuit, such that the amount of power transmitted bythe wireless power transmitter 1, 1-2, 1-3, 1-4, 1-5, 1-6, 1-7, or 1-8is decreased, whereby the amount of power received by the wireless powerreceiver 2 is further decreased as compared to the case in which onlythe frequency is adjusted.

FIG. 25 is a diagram schematically illustrating a process of changingadjusted variables in the wireless power transmitter 1, 1-1, 1-2, 1-3,1-4, 1-5, 1-6, 1-7, or 1-8 and the wireless power transmission method,according to an embodiment.

Referring to FIG. 25, in operation S2110, the controller 200, 201, 202,203, 204, 205, 206, 207, or 208 adjusts a frequency of the power whichis wirelessly transmitted, in response to the request signal input fromthe wireless power receiver 2. For example, the controller 200, 201,202, 203, 204, 205, 206, 207, or 208 adjusts the frequency of the powerwhich is wirelessly transmitted, by adjusting the frequency of thecontrol signal. That is, in a case in which the wireless power receiver2 requires a larger amount of power, the controller 200, 201, 202, 203,204, 205, 206, 207, or 208 decreases the frequency, and, in a case inwhich the wireless power receiver 2 requires a smaller amount of power,the controller 200, 201, 202, 203, 204, 205, 206, 207, or 208 increasesthe frequency. Operation S2110 is performed in the normal mode, and mayalso be performed in the boost mode.

Next, in operation S2120, it is determined whether a gain at theadjusted frequency is greater than a reference value. In this case, bydetermining whether the adjusted frequency reaches the reference value,it is also determined whether the adjusted frequency is greater than thereference value.

As a result of the determination in operation S2120, if it is determinedthat the gain at the adjusted frequency is less than the referencevalue, operation S2110 is performed.

As a result of the determination in operation S2120, if it is determinedthat a gain at a current frequency is equal to or greater than thereference value, the duty cycle of the control signal is adjusted inoperation S2130. In this case, the frequency is fixed. That is, in thecase in which operation S2110 is performed in the normal mode, theoperation mode is changed to the boost mode.

Next, even after the duty cycle is adjusted up to a limit value, it isdetermined in operation S2140 whether there is an additional powerrequest. For example, even after the duty cycle is increased up to thelimit value, it is determined whether the wireless power receiverrequires a larger amount of power.

As a result of the determination in operation S2140, if there is anadditional power request, the frequency is also adjusted in operationS2150. S2150 is performed in the boost mode.

Although FIG. 25 illustrates a case in which the amount of powerreceived by the wireless power receiver 2 is increased, by way ofexample, an operation of decreasing the amount of power received by thewireless power receiver 2 is implemented similarly to FIG. 25.

FIG. 26 is a diagram schematically illustrating a process of changingadjusted variables in the wireless power transmitter 1, 1-1, 1-2, 1-3,1-4, 1-5, 1-6, 1-7, or 1-8 and the wireless power transmission method,according to an embodiment.

Referring to FIG. 26, in operation S2210, the controller 200, 201, 202,203, 204, 205, 206, 207, or 208 adjusts the duty cycle of the controlsignal, in response to the request signal input from the wireless powerreceiver 2. For example, in a case in which the wireless power receiver2 requires a larger amount of power, the controller 200, 201, 202, 203,204, 205, 206, 207, or 208 increases the duty cycle, and in a case inwhich the wireless power receiver 2 requires a smaller amount of power,the controller 200, 201, 202, 203, 204, 205, 206, 207, or 208 decreasesthe duty cycle. Operation S2210 is performed in the boost mode and thereduction mode.

Next, in operation S2220, it is determined whether the adjusted dutycycle is less than a reference value. If it is determined in operationS2220 that the adjusted duty cycle is greater than the reference value,operation S2210 is performed.

If it is determined in operation S2220 that the adjusted duty cycle isequal to or less than the reference value, the frequency of the powerwhich is wirelessly transmitted is adjusted in operation S2230. In thiscase, the duty cycle is fixed to the reference value. In addition, thefrequency of the power which is wirelessly transmitted is adjusted byadjusting the frequency of the control signal. For example, the amountof power received by the wireless power receiver 2 is decreased byincreasing the frequency of the control signal. In the case in whichoperation S2210 is performed in the boost mode, operation S2230 may beperformed in the normal mode.

Next, in operation S2240, it is determined whether the adjustedfrequency is out of a reference range.

If it is determined in operation S2240 that the adjusted frequency isout of the reference range, the duty cycle is adjusted in operationS2250. For example, if it is determined in operation S2240 that theadjusted frequency is the reference value or more, the frequency isfixed to the reference value and the duty cycle is decreased inoperation S2250. In the case in which operation S2230 is performed inthe normal mode, operation S2250 may be performed in the reduction mode.Alternatively, all of the operations illustrated in FIG. 23 areperformed in the reduction mode.

Although FIG. 26 illustrates an example case in which the amount ofpower received by the wireless power receiver 2 is decreased, anoperation of increasing the amount of power received by the wirelesspower receiver 2 is implemented similarly to the manner illustrated inFIG. 26.

FIGS. 27 through 46 are diagrams each illustrating an operation ofdetermining, by the controller 200, 201, 202, 203, 204, 205, 206, 207,or 208, an operating frequency and an operating duty cycle. Thecontroller 200, 201, 202, 203, 204, 205, 206, 207, or 208 determines theoperating frequency and the operating duty cycle using the methodsillustrated in FIGS. 27 through 46, and outputs the control signals thatcontrol the switching elements using the determined operating frequencyand operating duty cycle.

Error information in each of FIGS. 27 through 46, which is informationreceived from the wireless power receiver 2, is information included inthe request signal req of FIGS. 7 through 15, and is also provided tothe controller 200, 201, 202, 203, 204, 205, 206, 207, or 208 in a formof an independent signal.

In each of FIGS. 27 through 46, the operating duty cycle means a dutycycle of the control signal that controls a low side switching element(i.e., the second switching element Q21, Q22, Q23, Q24, Q25, Q26, andQ28 and/or the fourth switching element Q44, Q45, and Q48 of FIGS. 8through 13, and 15) or the switching element of the boost converter(i.e., the sixth switching element Q67 of FIG. 14). Therefore, a dutycycle of each of the controlling signals that control a high sideswitching element (i.e., the first switching element Q11, Q12, Q13, Q14,Q15, Q16, and Q18 and/or the third switching element Q34, Q35, and Q38of FIGS. 8 through 13, and 15) is a 100−operating duty cycle d_c.

In addition, in each of FIGS. 27 through 46, the operating frequency isan operating frequency of at least one of the switching elements (i.e.,the switching elements Q11, Q21, Q12, Q22, Q13, Q23, Q14, Q24, Q34, Q44,Q15, Q25, Q35, Q45, Q16, Q26, Q17, Q27, Q18, Q28, Q38, and Q48 of FIGS.8 through 15) performing an inverter function.

In FIGS. 27 through 46, the first reference frequency f1 and the secondreference frequency f2 is set by the same method used to set the firstand second reference frequencies f1 and f2 illustrated in FIG. 6. Inaddition, a first reference duty cycle d1 and a second reference dutycycle d2 are also set similarly to the setting of the first referencefrequency f1 and the second reference frequency f2. For example, thefirst reference duty cycle d1, which is a lower limit value of the dutycycle which is adjustable in a first reduction mode, is determined byconsidering power transmission efficiency, element characteristics ofthe wireless power transmitter 1, 1-2, 1-3, 1-4, 1-5, 1-6, 1-7, or 1-8and the wireless power receiver 2, standards, or other protocols. Thesecond reference duty cycle d2, which is an upper limit value of theduty cycle which is adjustable in a first boost mode, is determined byconsidering power transmission efficiency, element characteristics ofthe wireless power transmitter 1, 1-2, 1-3, 1-4, 1-5, 1-6, 1-7, or 1-8and the wireless power receiver 2, degree of heat generated, standards,or other protocols. The second reference frequency f2 is greater thanthe first reference frequency f1, and the second reference duty cycle d2is greater than the first reference duty cycle d1. In addition, thefirst reference frequency f1 is less than or equal to a ping frequencyf_p, and the second reference frequency f2 is greater than or equal tothe ping frequency f_p. The first reference duty cycle d1 may be lessthan or equal to a ping duty cycle d_p, and the second reference dutycycle d2 may be greater than or equal to the ping duty cycle d_p. Inaddition, the first reference frequency f1 is greater than the resonancefrequency of the resonator 120, 121, 122, 123, 124, 125, 126, 127, or128 of FIGS. 7 through 15.

FIG. 27 is an operation flowchart illustrating an operation of thewireless power transmitter 1, 1-2, 1-3, 1-4, 1-5, 1-6, 1-7, or 1-8 orthe wireless power transmission method in a power transmission mode,according to an embodiment.

First, in operation S3101, the controller 200, 201, 202, 203, 204, 205,206, 207, or 208 sets the operating frequency f_c to the ping frequencyf_p, and sets the operating duty cycle d_c to the ping duty cycle d_p.Operation S3101 is performed in the detection mode.

Next, in operation S3201, the controller 200, 201, 202, 203, 204, 205,206, 207, or 208 calculates the operating frequency f_c based on theerror information received from the wireless power receiver 2. In thiscase, the operating duty cycle d_c is fixed to the ping duty cycle d_p.The error information is information regarding a difference between theamount of power required by the wireless power receiver 2 and the amountof power received by the wireless power receiver 2.

Next, in operation S3301, it is determined whether the calculatedoperating frequency f_c is greater than the first reference frequencyf1.

If it is determined in operation S3301 that the calculated operatingfrequency f_c is greater than the first reference frequency f1, thecontroller 200, 201, 202, 203, 204, 205, 206, 207, or 208 generates thecontrol signals using the calculated operating frequency f_c andoperating duty cycle d_c, and outputs the generated control signals inoperation S3701.

If it is determined in operation S3301 that the operating frequency f_cis less than or equal to the first reference frequency f1, thecontroller 200, 201, 202, 203, 204, 205, 206, 207, or 208 sets theoperating frequency f_c to the first reference frequency f1, andcalculates the operating duty cycle d_c based on the error informationin operation S3401.

After performing operation S3401, the controller 200, 201, 202, 203,204, 205, 206, 207, or 208 generates the control signals using thecalculated operating frequency f_c and operating duty cycle d_c, andoutputs the generated control signals in operation S3701.

FIG. 28 is a diagram illustrating a change in the operating frequencyand the operating duty cycle in the power transmission mode of thewireless power transmitter 1, 1-2, 1-3, 1-4, 1-5, 1-6, 1-7, or 1-8 andthe wireless power transmission method, according to an embodiment.

Referring to FIG. 28, first, in the normal mode n, the controller 200,201, 202, 203, 204, 205, 206, 207, or 208 adjusts the amount of powerreceived by the wireless power receiver 2 by varying the operatingfrequency f_c, in response to the error information received from thewireless power receiver 2. In this case, the operating duty cycle d_c isfixed to the ping duty cycle d_p. In the normal mode n, the operatingfrequency f_c is varied within the range of the first referencefrequency f1 to the second reference frequency f2.

When the amount of power received by the wireless power receiver 2 isless than the amount of power required by the wireless power receiver 2,even in the case in which the operating frequency f_c is decreased up tothe first reference frequency f1, the operation mode of the controller200, 201, 202, 203, 204, 205, 206, 207, or 208 is changed to the firstboost mode h1, and the controller 200, 201, 202, 203, 204, 205, 206,207, or 208 adjusts the operating duty cycle d_c after fixing theoperating frequency f_c to the first reference frequency f1. In thefirst boost mode h1, the operating duty cycle d_c is varied within therange of the ping duty cycle d_p to the second reference duty cycle d2.

An operation of FIG. 28 will be described below with reference to theamount of power required by the wireless power receiver 2, that is, aload amount.

With respect to FIG. 28, if the load amount is less than a firstreference load amount R11, the controller 200, 201, 202, 203, 204, 205,206, 207, or 208 is operated in the normal mode n. In the normal mode n,the controller 200, 201, 202, 203, 204, 205, 206, 207, or 208 fixes theoperating duty cycle d_c to the ping duty cycle d_p, and varies theoperating frequency f_c. In the normal mode, the operating frequency f_cis varied within the range of the first reference frequency f1 to thesecond reference frequency f2.

If the load amount is greater than the first reference load amount R11,the controller 200, 201, 202, 203, 204, 205, 206, 207, or 208 isoperated in the first boost mode h1. In the first boost mode h1, thecontroller 200, 201, 202, 203, 204, 205, 206, 207, or 208 fixes theoperating frequency f_c to the first reference frequency f1, and variesthe operating duty cycle d_c. In the first boost mode h1, the controller200, 201, 202, 203, 204, 205, 206, 207, or 208 varies the operating dutycycle d_c in the range of the ping duty cycle d_p to the second dutycycle.

FIG. 29 is an operation flowchart illustrating an operation of thewireless power transmitter 1, 1-2, 1-3, 1-4, 1-5, 1-6, 1-7, or 1-8 andthe wireless power transmission method in a power transmission mode,according to an embodiment.

First, in operation S3102, the controller 200, 201, 202, 203, 204, 205,206, 207, or 208 sets the operating frequency f_c to the ping frequencyf_p, and set the operating duty cycle d_c to the ping duty cycle d_p.Operation S3102 is performed in the detection mode.

Next, in operation S3202, the controller 200, 201, 202, 203, 204, 205,206, 207, or 208 calculates the operating frequency f_c based on theerror information received from the wireless power receiver 2. In thiscase, the operating duty cycle d_c is fixed to the ping duty cycle d_p.The error information error is information regarding a differencebetween the amount of power required by the wireless power receiver 2and the amount of power received by the wireless power receiver 2.

Next, in operation S3502, it is determined whether the calculatedoperating frequency f_c is less than the second reference frequency f2.

If it is determined in operation S3502 that the calculated operatingfrequency f_c is less than the second reference frequency f2, thecontroller 200, 201, 202, 203, 204, 205, 206, 207, or 208 generates thecontrol signals using the calculated operating frequency f_c andoperating duty cycle d_c, and outputs the generated control signals inoperation S3702.

Alternatively, if it is determined in operation S3502 that the operatingfrequency f_c is greater than or equal to the second reference frequencyf2, the controller 200, 201, 202, 203, 204, 205, 206, 207, or 208 setsthe operating frequency f_c to the second reference frequency f2, andcalculates the operating duty cycle d_c based on the error informationerror in operation S3602.

After performing operation S3602, the controller 200, 201, 202, 203,204, 205, 206, 207, or 208 generates the control signals using thecalculated operating frequency f_c and operating duty cycle d_c, andoutputs the generated control signals in operation S3702.

FIG. 30 is a diagram illustrating a change in the operating frequencyand the operating duty cycle in the power transmission mode of thewireless power transmitter 1, 1-2, 1-3, 1-4, 1-5, 1-6, 1-7, or 1-8 andthe wireless power transmission method, according to an embodiment.

Referring to FIG. 30, first, in the normal mode n, the controller 200,201, 202, 203, 204, 205, 206, 207, or 208 adjusts the amount of powerreceived by the wireless power receiver 2 by varying the operatingfrequency f_c, in response to the error information received from thewireless power receiver 2. In this case, the operating duty cycle d_c isfixed to the ping duty cycle d_p.

When the amount of power received by the wireless power receiver 2 isgreater than the amount of power required by the wireless power receiver2, even in the case in which the operating frequency f_c is increased upto the second reference frequency f2, the operation mode of thecontroller 200, 201, 202, 203, 204, 205, 206, 207, or 208 is changed toa first reduction mode l1, and the controller 200, 201, 202, 203, 204,205, 206, 207, or 208 adjusts the operating duty cycle d_c after fixingthe operating frequency f_c to the second reference frequency f2.

An operation of FIG. 30 will be described below with reference to theamount of power required by the wireless power receiver 2, that is, aload amount.

Referring to FIG. 30, if the load amount is greater than a secondreference load amount R22, the controller 200, 201, 202, 203, 204, 205,206, 207, or 208 is operated in the normal mode n. In the normal mode n,the controller 200, 201, 202, 203, 204, 205, 206, 207, or 208 fixes theoperating duty cycle d_c to the ping duty cycle d_p, and varies theoperating frequency f_c. In the normal mode, the operating frequency f_cis varied within the range of the first reference frequency f1 to thesecond reference frequency f2.

If the load amount is less than the second reference load amount R22,the controller 200, 201, 202, 203, 204, 205, 206, 207, or 208 isoperated in the first reduction mode l1. In the first reduction mode l1,the controller 200, 201, 202, 203, 204, 205, 206, 207, or 208 fixes theoperating frequency f_c to the second reference frequency f2, and variesthe operating duty cycle d_c. In the first reduction mode l1, thecontroller 200, 201, 202, 203, 204, 205, 206, 207, or 208 varies theoperating duty cycle d_c in the range of the ping duty cycle d_p to thefirst duty cycle d1.

FIG. 31 is an operation flowchart illustrating an operation of thewireless power transmitter 1, 1-2, 1-3, 1-4, 1-5, 1-6, 1-7, or 1-8 andthe wireless power transmission method, according to an embodiment.

First, in operation S3103, the controller 200, 201, 202, 203, 204, 205,206, 207, or 208 sets the operating frequency f_c to the ping frequencyf_p, and sets the operating duty cycle d_c to the ping duty cycle d_p.Operation S3103 is performed in the detection mode.

Next, in operation S3203, the controller 200, 201, 202, 203, 204, 205,206, 207, or 208 calculates the operating frequency f_c based on theerror information received from the wireless power receiver. In thiscase, the operating duty cycle d_c is fixed to the ping duty cycle d_p.The error information is information regarding a difference between theamount of power required by the wireless power receiver 2 and the amountof power received by the wireless power receiver 2.

Next, in operation S3303, it is determined whether the calculatedoperating frequency f_c is greater than the first reference frequencyf1.

If it is determined in operation S3303 that the operating frequency f_cis less than or equal to the first reference frequency f1, thecontroller 200, 201, 202, 203, 204, 205, 206, 207, or 208 sets theoperating frequency f_c to the first reference frequency f1, andcalculates the operating duty cycle d_c based on the error informationin operation S3403.

After performing operation S3403, the controller 200, 201, 202, 203,204, 205, 206, 207, or 208 generates the control signals using thecalculated operating frequency f_c and operating duty cycle d_c, andoutputs the generated control signals in operation S3703.

Alternatively, if it is determined in operation S3303 that thecalculated operating frequency f_c is greater than the first referencefrequency f1, it is determined whether the calculated operatingfrequency f_c is less than the second reference frequency f2 inoperation S3503.

If it is determined in operation S3503 that the calculated operatingfrequency f_c is less than the second reference frequency f2, that is,the operating frequency f_c calculated in operation S3203 is a valuebetween the first reference frequency f1 and the second referencefrequency f2, the controller 200, 201, 202, 203, 204, 205, 206, 207, or208 generates the control signals using the calculated operatingfrequency f_c and operating duty cycle d_c, and outputs the generatedcontrol signals in operation S3703.

Alternatively, if it is determined in operation S3503 that the operatingfrequency f_c is greater than or equal to the second reference frequencyf2, the controller 200, 201, 202, 203, 204, 205, 206, 207, or 208 setsthe operating frequency f_c to the second reference frequency f2, andcalculates the operating duty cycle d_c based on the error informationin operation S3603.

After performing S3603, the controller 200, 201, 202, 203, 204, 205,206, 207, or 208 generates the control signals using the calculatedoperating frequency f_c and operating duty cycle d_c, and outputs thegenerated control signals in operation S3703.

FIG. 32 is a diagram illustrating a change in the operating frequencyand the operating duty cycle in the power transmission mode of thewireless power transmitter 1, 1-2, 1-3, 1-4, 1-5, 1-6, 1-7, or 1-8 andthe wireless power transmission method, according to an embodiment.

Referring to FIG. 32, first, in the normal mode n, the controller 200,201, 202, 203, 204, 205, 206, 207, or 208 adjusts the amount of powerreceived by the wireless power receiver 2 by varying the operatingfrequency f_c, in response to the error information received from thewireless power receiver 2. In this case, the operating duty cycle d_c isfixed to the ping duty cycle d_p.

When the amount of power received by the wireless power receiver 2 isless than the amount of power required by the wireless power receiver 2,even in the case in which the operating frequency f_c is decreased up tothe first reference frequency f1, the operation mode of the controller200, 201, 202, 203, 204, 205, 206, 207, or 208 is changed to the firstboost mode h1, and the controller 200, 201, 202, 203, 204, 205, 206,207, or 208 adjusts the operating duty cycle d_c after fixing theoperating frequency f_c to the first reference frequency f1.

When the amount of power received by the wireless power receiver 2 isgreater than the amount of power required by the wireless power receiver2, even in the case in which the operating frequency f_c is increased upto the second reference frequency f2, the operation mode of thecontroller 200, 201, 202, 203, 204, 205, 206, 207, or 208 is changed toa first reduction mode l1, and the controller 200, 201, 202, 203, 204,205, 206, 207, or 208 adjusts the operating duty cycle d_c after fixingthe operating frequency f_c to the second reference frequency f2.

An operation of FIG. 32 will be described below with reference to theamount of power required by the wireless power receiver 2, that is, aload amount.

If the load amount is less than a first reference load amount R13 and isgreater than a second reference load amount R23, the controller 200,201, 202, 203, 204, 205, 206, 207, or 208 is operated in the normal moden. In the normal mode n, the controller 200, 201, 202, 203, 204, 205,206, 207, or 208 fixes the operating duty cycle d_c to the ping dutycycle d_p, and varies the operating frequency f_c. In the normal mode,the operating frequency f_c is varied within the range of the firstreference frequency f1 to the second reference frequency f2.

If the load amount is greater than the first reference load amount R13,the controller 200, 201, 202, 203, 204, 205, 206, 207, or 208 isoperated in the first boost mode h1. In the first boost mode h1, thecontroller 200, 201, 202, 203, 204, 205, 206, 207, or 208 fixes theoperating frequency f_c to the first reference frequency f1, and variesthe operating duty cycle d_c. In the first boost mode h1, the controller200, 201, 202, 203, 204, 205, 206, 207, or 208 varies the operating dutycycle d_c in the range of the ping duty cycle d_p to the second dutycycle d2.

If the load amount is less than the second reference load amount R22,the controller 200, 201, 202, 203, 204, 205, 206, 207, or 208 isoperated in the first reduction mode l1. In the first reduction mode l1,the controller 200, 201, 202, 203, 204, 205, 206, 207, or 208 fixes theoperating frequency f_c to the second reference frequency f2, and variesthe operating duty cycle d_c. In the first reduction mode l1, thecontroller 200, 201, 202, 203, 204, 205, 206, 207, or 208 varies theoperating duty cycle d_c in the range of the ping duty cycle d_p to thefirst duty cycle d1.

FIG. 33 is an operation flowchart illustrating an operation of thewireless power transmitter1, 1-2, 1-3, 1-4, 1-5, 1-6, 1-7, or 1-8 andthe wireless power transmission method in a power transmission mode,according to an embodiment.

Referring to FIG. 33, first, the controller 200, 201, 202, 203, 204,205, 206, 207, or 208 sets the operating frequency f_c to the pingfrequency f_p, and sets the operating duty cycle d_c to the ping dutycycle d_p in operation S3104. Operation S3104 is performed in thedetection mode.

Next, in operation S3204, the controller 200, 201, 202, 203, 204, 205,206, 207, or 208 calculates the operating frequency f_c based on theerror information received from the wireless power receiver 2. In thiscase, the operating duty cycle d_c is fixed to the ping duty cycle d_p.The error information is information regarding a difference between theamount of power required by the wireless power receiver 2 and the amountof power received by the wireless power receiver 2.

Next, in operation S3304, it is determined whether the calculatedoperating frequency f_c is greater than the first reference frequencyf1.

If it is determined in operation S3304 that the operating frequency f_cis less than or equal to the first reference frequency f1, thecontroller 200, 201, 202, 203, 204, 205, 206, 207, or 208 sets theoperating frequency f_c to the first reference frequency f1, andcalculates the operating duty cycle d_c based on the error informationin operation S3404.

Next, in operation S3424, it is determined whether the calculatedoperating duty cycle d_c is greater than the second reference duty cycled2.

If it is determined in S3424 that the calculated operating duty cycled_c is less than or equal to the second reference duty cycle d2, thecontroller 200, 201, 202, 203, 204, 205, 206, 207, or 208 generates thecontrol signals using the calculated operating frequency f_c andoperating duty cycle d_c, and outputs the generated control signals inoperation S3704.

Alternatively, if it is determined in operation S3424 that thecalculated operating duty cycle d_c is greater than the second referenceduty cycle d2, the controller 200, 201, 202, 203, 204, 205, 206, 207, or208 fixes the operating duty cycle d_c to the second duty cycle, andagain calculates the operating frequency f_c based on the errorinformation in operation S3444.

After performing operation S3444, the controller 200, 201, 202, 203,204, 205, 206, 207, or 208 generates the control signals using thecalculated operating frequency f_c and operating duty cycle d_c, andoutputs the generated control signals in operation S3704.

If it is determined in operation S3304 that the calculated operatingfrequency f_c is greater than the first reference frequency f1, it isdetermined whether the calculated operating frequency f_c is less thanthe second reference frequency f2 in operation S3504.

If it is determined in operation S3504 that the calculated operatingfrequency f_c is less than the second reference frequency f2, that is,the operating frequency f_c calculated in operation S3204 is a valuebetween the first reference frequency f1 and the second referencefrequency f2, the controller 200, 201, 202, 203, 204, 205, 206, 207, or208 generates the control signals using the calculated operatingfrequency f_c and operating duty cycle d_c, and outputs the generatedcontrol signals in operation S3704.

If it is determined in operation S3504 that the operating frequency f_cis greater than or equal to the second reference frequency f2, thecontroller 200, 201, 202, 203, 204, 205, 206, 207, or 208 sets theoperating frequency f_c to the second reference frequency f2, andcalculates the operating duty cycle d_c based on the error informationerror in operation S3604.

After performing S3604, the controller 200, 201, 202, 203, 204, 205,206, 207, or 208 generates the control signals using the calculatedoperating frequency f_c and operating duty cycle d_c, and outputs thegenerated control signals in operation S3704.

FIG. 34 is a diagram illustrating a change in the operating frequencyand the operating duty cycle in the power transmission mode of thewireless power transmitter 1, 1-2, 1-3, 1-4, 1-5, 1-6, 1-7, or 1-8 andthe wireless power transmission method, according to an embodiment.

First, in the normal mode n, the controller 200, 201, 202, 203, 204,205, 206, 207, or 208 adjusts the amount of power received by thewireless power receiver 2 by varying the operating frequency f_c, inresponse to the error information received from the wireless powerreceiver 2. In this case, the operating duty cycle d_c is fixed to theping duty cycle d_p. In the normal mode n, the operating frequency f_cis varied within the range of the first reference frequency f1 to thesecond reference frequency f2.

When the amount of power received by the wireless power receiver 2 isless than the amount of power required by the wireless power receiver 2,even in the case in which the operating frequency f_c is decreased up tothe first reference frequency f1, the operation mode of the controller200, 201, 202, 203, 204, 205, 206, 207, or 208 is changed to the firstboost mode h1, and the controller 200, 201, 202, 203, 204, 205, 206,207, or 208 adjusts the operating duty cycle d_c after fixing theoperating frequency f_c to the first reference frequency f1. In thefirst boost mode h1, the operating duty cycle d_c is varied within therange of the ping duty cycle d_p to the second reference duty cycle d2.

When the amount of power received by the wireless power receiver 2 isless than the amount of power required by the wireless power receiver 2,even in the case in which the operating duty cycle d_c is increased upto the second reference duty cycle d2 in the first boost mode h1, theoperation mode of the controller 200, 201, 202, 203, 204, 205, 206, 207,or 208 is changed to a second boost mode h2, and the controller 200,201, 202, 203, 204, 205, 206, 207, or 208 adjusts the amount of powerreceived by the wireless power receiver 2 by varying the operatingfrequency f_c. In the second boost mode h2, the operating duty cycle d_cis fixed to the second reference duty cycle d2. In the second boost modeh2, the operating frequency f_c is varied within the range of the firstreference frequency f1 to a minimum frequency f_min.

In the normal mode, when the amount of power received by the wirelesspower receiver 2 is greater than the amount of power required by thewireless power receiver 2, even in the case in which the operatingfrequency f_c is increased up to the second reference frequency f2, theoperation mode of the controller 200, 201, 202, 203, 204, 205, 206, 207,or 208 is changed to the first reduction mode l1, and the controller200, 201, 202, 203, 204, 205, 206, 207, or 208 adjusts the operatingduty cycle d_c after fixing the operating frequency f_c to the secondreference frequency f2. In the first reduction mode l1, the operatingduty cycle d_c is varied within the range of the first reference dutycycle d1 to the ping duty cycle d_p.

An operation of FIG. 34 will be described below with reference to theamount of power required by the wireless power receiver 2, that is, aload amount.

If the load amount is less than a first reference load amount R14 and isgreater than a second reference load amount R24, the controller 200,201, 202, 203, 204, 205, 206, 207, or 208 is operated in the normalmode. If the load amount is greater than the first reference amount R14and is less than a third reference load amount R34, the controller 200,201, 202, 203, 204, 205, 206, 207, or 208 is operated in the first boostmode h1. If the load amount is less than the second reference amountR24, the controller 200, 201, 202, 203, 204, 205, 206, 207, or 208 isoperated in the first reduction mode l1. The operations in the firstreduction mode l1, the normal mode n, and the first boost mode h1 arethe same as those described with respect to FIG. 32.

If the load amount is greater than the third reference load amount R34,the controller 200, 201, 202, 203, 204, 205, 206, 207, or 208 isoperated in the second boost mode h2. In the second boost mode h2, thecontroller 200, 201, 202, 203, 204, 205, 206, 207, or 208 fixes theoperating duty cycle d_c to the second reference duty cycle d2, andvaries the operating frequency f_c. In the second boost mode h2, theoperating frequency f_c is varied within the range of the firstreference frequency f1 to the minimum frequency f_min.

FIG. 35 is an operation flowchart illustrating an operation of thewireless power transmitter 1, 1-2, 1-3, 1-4, 1-5, 1-6, 1-7, or 1-8 andthe wireless power transmission method in a power transmission mode,according to an embodiment.

Operations S3105, S3205, S3305, S3405, S3425, S3445, S3505, S3605, andS3705 are the same as operations S3104, S3204, S3304, S3404, S3424,S3444, S3504, S3604, and S3704 described in FIG. 33, respectively.

After the operating frequency f_c is calculated in operation S3445, thecontroller 200, 201, 202, 203, 204, 205, 206, 207, or 208 determineswhether the operating frequency f_c is less than the minimum frequencyf_min in operation S3465.

If it is determined in operation S3465 that the operating frequency f_ccalculated in S3445 is greater than or equal to the minimum frequencyf_min, the controller 200, 201, 202, 203, 204, 205, 206, 207, or 208generates the control signals using the calculated operating frequencyf_c and operating duty cycle d_c, and outputs the generated controlsignals in operation S3705.

Alternatively, if it is determined in operation S3465 that the operatingfrequency f_c calculated in operation S3445 is less than the minimumfrequency f_min, the controller 200, 201, 202, 203, 204, 205, 206, 207,or 208 sets the operating frequency to the minimum frequency f_min, andcalculates the operating duty cycle d_c based on the error informationerror in operation S3485. In operation S3485, the operating duty cycled_c is greater than the second reference duty cycle d2. For example, theoperating duty cycle d_c has a value of 50% or more.

After performing operation S3485, the controller 200, 201, 202, 203,204, 205, 206, 207, or 208 generates the control signals using thecalculated operating frequency f_c and operating duty cycle d_c, andoutputs the generated control signals in operation S3705.

FIG. 36 is a diagram illustrating a change in the operating frequencyand the operating duty cycle in the power transmission mode of thewireless power transmitter 1, 1-2, 1-3, 1-4, 1-5, 1-6, 1-7, or 1-8 andthe wireless power transmission method, according to an embodiment.

In FIG. 36, the operations in the first reduction mode l1, the normalmode n, the first boost mode h1, and the second boost mode h2 are thesame as those described in FIG. 34.

Referring to FIG. 36, in the second boost mode h2, when the amount ofpower received by the wireless power receiver 2 is less than the amountof power required by the wireless power receiver 2, even in the case inwhich the operating frequency is decreased up to the minimum frequencyf_min, the operation mode of the controller 200, 201, 202, 203, 204,205, 206, 207, or 208 is changed to a third boost mode h3. In the thirdboost mode h3, the controller 200, 201, 202, 203, 204, 205, 206, 207, or208 fixes the operating frequency f_c to the minimum frequency f_min,and increases the operating duty cycle d_c. In the third boost mode h3,the operating duty cycle d_c has a value of the second reference dutycycle d2 or more. For example, in the third boost mode h3, the operatingduty cycle d_c is adjusted in the range of the second reference dutycycle d2 or more to the maximum duty cycle d_max or less. The secondreference duty cycle d2 and the maximum duty cycle d_max are set by auser in consideration of limitations based on standards and otherprotocols, or an environment in which the wireless power transmitter 1,1-2, 1-3, 1-4, 1-5, 1-6, 1-7, or 1-8 is used.

That is, if the load amount is greater than a fifth reference loadamount R55, the controller 200, 201, 202, 203, 204, 205, 206, 207, or208 is operated in the third boost mode h3.

FIG. 37 is an operation flowchart illustrating an operation of thewireless power transmitter 1, 1-2, 1-3, 1-4, 1-5, 1-6, 1-7, or 1-8 andthe wireless power transmission method in a power transmission mode,according to an embodiment.

In FIG. 37, operations S3106, S3206, S3306, S3406, S3506, S3606, andS3706 are the same as operations S3103, S3203, S3303, S3403, S3503,S3603, and S3703 described in FIG. 28, respectively.

After the operating duty cycle d_c is calculated in operation S3606, thecontroller 200, 201, 202, 203, 204, 205, 206, 207, or 208 determineswhether the calculated operating duty cycle d_c is less than the firstreference duty cycle d1 in operation S3626.

If it is determined in operation S3626 that the operating duty cycle d_cis greater than or equal to the first reference duty cycle d1, thecontroller 200, 201, 202, 203, 204, 205, 206, 207, or 208 generates thecontrol signals using the operating frequency f_c and the operating dutycycle d_c calculated in operation S3606, and outputs the generatedcontrol signals in operation S3706.

Alternatively, if it is determined in operation S3626 that the operatingduty cycle d_c is less than the first reference duty cycle d1, thecontroller 200, 201, 202, 203, 204, 205, 206, 207, or 208 fixes theoperating duty cycle d_c to the first reference duty cycle d1, andcalculates the operating frequency f_c based on the error informationerror in operation S3646.

After performing operation S3646, the controller 200, 201, 202, 203,204, 205, 206, 207, or 208 generates the control signals using thecalculated operating frequency f_c and operating duty cycle d_c, andoutputs the generated control signals in operation S3706.

FIG. 38 is a diagram illustrating a change in the operating frequencyand the operating duty cycle in the power transmission mode of thewireless power transmitter 1, 1-2, 1-3, 1-4, 1-5, 1-6, 1-7, or 1-8 andthe wireless power transmission method, according to an embodiment.

Referring to FIG. 38, the operations in the first reduction mode l1, thenormal mode n, and the first boost mode h1 are the same as thosedescribed in FIG. 32.

In the first reduction mode l1, when the amount of power received by thewireless power receiver 2 is greater than the amount of power requiredby the wireless power receiver 2, even in the case in which theoperating duty cycle d_c is decreased up to the first reference dutycycle d1, the operation mode of the controller 200, 201, 202, 203, 204,205, 206, 207, or 208 is changed to a second reduction mode l2. In thesecond reduction mode l2, the controller 200, 201, 202, 203, 204, 205,206, 207, or 208 fixes the operating duty cycle d_c to the firstreference duty cycle d1, and varies the operating frequency f_c. In thesecond reduction mode l2, the operating frequency f_c is varied withinthe range of the second reference frequency f2 to the maximum frequencyf_max.

That is, if the load amount is greater than a fourth reference loadamount R46, the controller 200, 201, 202, 203, 204, 205, 206, 207, or208 is operated in the second reduction mode l2.

FIG. 39 is an operation flowchart illustrating an operation of thewireless power transmitter 1, 1-2, 1-3, 1-4, 1-5, 1-6, 1-7, or 1-8 andthe wireless power transmission method in a power transmission mode,according to an embodiment.

In FIG. 39, operations S3107, S3207, S3307, S3407, S3507, S3607, andS3707 are the same as operations S3103, S3203, S3303, S3403, S3503,S3603, and S3703 described in FIG. 31, respectively.

Referring to FIG. 39, after the operating duty cycle d_c is calculatedin operation S3407, the controller 200, 201, 202, 203, 204, 205, 206,207, or 208 determines whether or not the calculated operating dutycycle d_c is greater than the second reference duty cycle d2 inoperation S3427.

If it is determined in operation S3427 that the calculated operatingduty cycle d_c is less than or equal to the second reference duty cycled2, the controller 200, 201, 202, 203, 204, 205, 206, 207, or 208generates the control signals using the operating frequency f_c and theoperating duty cycle d_c which are calculated in operation S3407, andoutputs the generated control signals in operation S3707.

Alternatively, if it is determined in operation S3427 that thecalculated operating duty cycle d_c is greater than the second referenceduty cycle d2, the controller 200, 201, 202, 203, 204, 205, 206, 207, or208 fixes the operating duty cycle d_c to the second duty cycle, andagain calculates the operating frequency f_c based on the errorinformation in operation S3447.

After performing operation S3447, the controller 200, 201, 202, 203,204, 205, 206, 207, or 208 generates the control signals using thecalculated operating frequency f_c and operating duty cycle d_c, andoutputs the generated control signals in operation S3707.

After the operating duty cycle d_c is calculated in operation S3607, thecontroller 200, 201, 202, 203, 204, 205, 206, 207, or 208 determineswhether the calculated operating duty cycle d_c is less than the firstreference duty cycle d1 in operation S3627.

If it is determined in operation S3627 that the operating duty cycle d_cis greater than or equal to the first reference duty cycle d1, thecontroller 200, 201, 202, 203, 204, 205, 206, 207, or 208 generates thecontrol signals using the operating frequency f_c and the operating dutycycle d_c which are calculated in operation S3607, and outputs thegenerated control signals in operation S3707.

Alternatively, if it is determined in operation S3627 that the operatingduty cycle d_c is less than the first reference duty cycle d1, thecontroller 200, 201, 202, 203, 204, 205, 206, 207, or 208 fixes theoperating duty cycle d_c to the first reference duty cycle d1, andcalculates the operating frequency f_c based on the error informationerror in operation S3647.

After performing operation S3647, the controller 200, 201, 202, 203,204, 205, 206, 207, or 208 generates the control signals using thecalculated operating frequency f_c and operating duty cycle d_c, andoutputs the generated control signals in operation S3707.

FIG. 40 is a diagram illustrating a change in the operating frequencyand the operating duty cycle in the power transmission mode of thewireless power transmitter 1, 1-2, 1-3, 1-4, 1-5, 1-6, 1-7, or 1-8 andthe wireless power transmission method, according to an embodiment.

In FIG. 40, the operations in the first reduction mode l1, the normalmode n, and the first boost mode h1 are the same as those described inFIG. 32.

Referring to FIG. 40, in the first reduction mode l1, when the amount ofpower received by the wireless power receiver 2 is greater than theamount of power required by the wireless power receiver 2, even in thecase in which the operating duty cycle d_c is decreased up to the firstreference duty cycle d1, the operation mode of the controller 200, 201,202, 203, 204, 205, 206, 207, or 208 is changed to a second reductionmode l2. In the second reduction mode l2, the controller 200, 201, 202,203, 204, 205, 206, 207, or 208 fixes the operating duty cycle d_c tothe first reference duty cycle d1, and varies the operating frequencyf_c. In the second reduction mode l2, the operating frequency f_c isvaried within the range of the second reference frequency f2 to themaximum frequency f_max.

That is, if the load amount is greater than a fourth reference loadamount R47, the controller 200, 201, 202, 203, 204, 205, 206, 207, or208 is operated in the second reduction mode l2.

When the amount of power received by the wireless power receiver 2 isless than the amount of power required by the wireless power receiver 2,even in the case in which the operating duty cycle d_c is increased upto the second reference duty cycle d2 in the first boost mode h1, theoperation mode of the controller 200, 201, 202, 203, 204, 205, 206, 207,or 208 is changed to a second boost mode h2, and the controller 200,201, 202, 203, 204, 205, 206, 207, or 208 adjusts the amount of powerreceived by the wireless power receiver 2 by varying the operatingfrequency f_c. In the second boost mode h2, the operating duty cycle d_cis fixed to the second reference duty cycle d2. In the second boost modeh2, the operating frequency f_c is varied within the range of the firstreference frequency f1 to a minimum frequency f_min.

That is, if the load amount is greater than a third reference loadamount R37, the controller 200, 201, 202, 203, 204, 205, 206, 207, or208 is operated in the second boost mode h2.

FIG. 41 is an operation flowchart illustrating an operation of thewireless power transmitter 1, 1-2, 1-3, 1-4, 1-5, 1-6, 1-7, or 1-8 andthe wireless power transmission method in a power transmission mode,according to an embodiment.

In FIG. 41, operations S3108, S3208, S3308, S3408, S3428, S3438, S3508,and S3708 are the same as operations S3104, S3204, S3304, S3404, S3424,S3434, S3504, and S3704 described in FIG. 33, respectively.

If it is determined in operation S3508 that the operating frequency f_ccalculated in operation S3208 is less than the second referencefrequency f2, the controller 200, 201, 202, 203, 204, 205, 206, 207, or208 sets the operating frequency f_c to the second reference frequencyf2, fixes an operating duty cycle d_c1 of a first leg (i.e., an on-dutycycle of the second control signal con24, con25, and con28 (FIGS. 11,12, and 15)) to the ping duty cycle d_p, and calculates an operatingduty cycle d_c2 of a second leg (i.e., an on-duty cycle of the fourthcontrol signal con44, con45, and con48 (FIGS. 11, 12, and 15)) inoperation.

After performing operation S3608, the controller 200, 201, 202, 203,204, 205, 206, 207, or 208 generates the control signals using thecalculated operating frequency f_c and operating duty cycle d_c1 andd_c2, and outputs the generated control signals in operation S3708.

FIG. 42 is a diagram illustrating a change in the operating frequencyand the operating duty cycle in the power transmission mode of thewireless power transmitter 1, 1-2, 1-3, 1-4, 1-5, 1-6, 1-7, or 1-8 andthe wireless power transmission method, according to an embodiment.

In FIG. 42, the operations in the normal mode n, the first boost modeh1, and the second boost mode h2 are the same as those described in FIG.31.

Referring to FIG. 42, in the normal mode n, when the amount of powerreceived by the wireless power receiver 2 is greater than the amount ofpower required by the wireless power receiver 2, even in the case inwhich the operating frequency f_c is increased up to the secondreference frequency f2, the operation mode of the controller 200, 201,202, 203, 204, 205, 206, 207, or 208 is changed to a third reductionmode l3. In the third reduction mode l3, the controller 200, 201, 202,203, 204, 205, 206, 207, or 208 fixes the operating frequency f_c to thesecond reference frequency f2, fixes the operating duty cycle d_c1 ofthe first leg (i.e., the on-duty cycle of the second control signalscon24, con25, and con28 (FIGS. 11, 12, and 15)) to the ping duty cycled_p, and adjusts the operating duty cycle d_c2 of the second leg (i.e.,the on-duty cycle of the fourth control signal con44, con45, and con48(FIGS. 11, 12, and 15)). In the third reduction mode l3, the operatingduty cycle d_c2 of the second leg is varied within the range of the pingduty cycle d_p to (100−ping duty cycle d_p).

That is, if the load amount is less than a second reference load amountR28, the controller 200, 201, 202, 203, 204, 205, 206, 207, or 208 isoperated in the third reduction mode l3.

FIG. 43 is an operation flowchart illustrating an operation of thewireless power transmitter 1, 1-2, 1-3, 1-4, 1-5, 1-6, 1-7, or 1-8 andthe wireless power transmission in a power transmission mode, accordingto an embodiment.

In FIG. 43, operations S3109, S3209, S3309, S3409, S3429, S3439, S3509,and S3709 are the same as operations S3104, S3204, S3304, S3404, S3424,S3434, S3504, and S3704 described in FIG. 33, respectively.

Referring to FIG. 43, if it is determined in operation S3509 that theoperating frequency f_c calculated in operation S3209 is less than thesecond reference frequency f2, the controller 200, 201, 202, 203, 204,205, 206, 207, or 208 sets the operating duty cycle d_c to an operatingduty cycle at which the converter 111, 112, 113, 114, 115, 116, or 117is operated as the half-bridge, and calculates the operating frequencyf_c based on the error information in operation S3609.

After performing operation S3609, the controller 200, 201, 202, 203,204, 205, 206, 207, or 208 generates the control signals using thecalculated operating frequency f_c and operating duty cycle d_c, andoutputs the generated control signals in operation S3709).

FIG. 44 is a diagram illustrating a change in the operating frequencyand the operating duty cycle in the power transmission mode of thewireless power transmitter 1, 1-2, 1-3, 1-4, 1-5, 1-6, 1-7, or 1-8 andthe wireless power transmission method, according to an embodiment.

In FIG. 44, the operations in the normal mode n, the first boost modeh1, and the second boost mode h2 are the same as those described in FIG.34.

In the normal n, when the amount of power received by the wireless powerreceiver 2 is greater than the amount of power required by the wirelesspower receiver 2, even in the case in which the operating frequency f_cis increased up to the second reference frequency f2, the operation modeof the controller 200, 201, 202, 203, 204, 205, 206, 207, or 208 ischanged to a fourth reduction mode l4. In the fourth reduction mode l4,the controller 200, 201, 202, 203, 204, 205, 206, 207, or 208 fixes theoperating duty cycle d_c1 of the first leg (i.e., the on-duty cycle ofthe second control signal con24, con25, and con28 (FIGS. 11, 12, and15)) to the ping duty cycle d_p, fixes the operating duty cycle d_c2 ofthe second leg (i.e., the duty cycle of the fourth control signal con44,con45, and con48 (FIGS. 11, 12, and 15)) to 100%, and adjusts theoperating frequency f_c. In the fourth reduction mode l4, the operatingfrequency f_c is varied within the range of the second referencefrequency f2 to the maximum frequency f_max.

That is, if the load amount is less than a second reference load amountR29, the controller 200, 201, 202, 203, 204, 205, 206, 207, or 208 isoperated in the fourth reduction mode l4.

FIG. 45 is an operation flowchart illustrating an operation of thewireless power transmitter 1, 1-2, 1-3, 1-4, 1-5, 1-6, 1-7, or 1-8 andthe wireless power transmission method, according to an embodiment.

In FIG. 45, operations S3110, S3210, S3310, S3410, S3430, S3450, S3510,and S3710 are the same as operations S3104, S3204, S3304, S3404, S3424,S3434, S3504, and S3704 described in FIG. 33, respectively.

Referring to FIG. 45, if it is determined in operation S3510 that theoperating frequency f_c calculated in S3210 is less than the secondreference frequency f2, the controller 200, 201, 202, 203, 204, 205,206, 207, or 208 sets the operating frequency f_c to the secondreference frequency f2, fixes the operating duty cycle d_c1 of the firstleg (i.e., the duty cycle of the second control signal con24, con25, andcon28 (FIGS. 11, 12, and 15)) to the ping duty cycle d_p, and calculatesthe operating duty cycle d_c2 of the second leg (i.e., the duty cycle ofthe fourth control signal con44, con45, and con48 (FIGS. 11, 12, and15)) in operation S3610.

After performing operation S3610, the controller 200, 201, 202, 203,204, 205, 206, 207, or 208 determines whether the calculated operatingduty cycle d_c2 of the second leg is less than the ping duty cycle d_pin operation S3630.

If it is determined in operation S3630 that the operating duty cycled_c2 of the second leg calculated in S3610 is greater than or equal tothe ping duty cycle d_p, the controller 200, 201, 202, 203, 204, 205,206, 207, or 208 generates the control signals using the operatingfrequency f_c and the operating duty cycle d_c which are calculated inoperation S3610, and outputs the generated control signals in operationS3710.

Alternatively, if it is determined in operation S3630 that the operatingduty cycle d_c2 of the second leg calculated in operation S3610 is lessthan the ping duty cycle d_p, the controller 200, 201, 202, 203, 204,205, 206, 207, or 208 sets the operating duty cycle d_c to an operatingduty cycle at which the converter 111, 112, 113, 114, 115, 116, or 117is operated as the half-bridge, and calculates the operating frequencyf_c based on the error information in operation S3650. In operationS3650, the operating duty cycle d_c1 of the first leg is fixed to theping duty cycle d_p, and the operating duty cycle d_c2 of the second legis fixed to 100%.

After performing operation S3650, the controller 200, 201, 202, 203,204, 205, 206, 207, or 208 generates the control signals using thecalculated operating frequency f_c and operating duty cycle d_c, andoutputs the generated control signals in operation S3710.

FIG. 46 is a diagram illustrating a change in the operating frequencyand the operating duty cycle in the power transmission mode of thewireless power transmitter 1, 1-2, 1-3, 1-4, 1-5, 1-6, 1-7, or 1-8 andthe wireless power transmission method, according to an embodiment.

In FIG. 46, the operations in the normal mode n, the first boost modeh1, and the second boost mode h2 are the same as those described in FIG.34.

In the normal mode n, when the amount of power received by the wirelesspower receiver 2 is greater than the amount of power required by thewireless power receiver 2, even in the case in which the operatingfrequency f_c is increased up to the second reference frequency f2, theoperation mode of the controller 200, 201, 202, 203, 204, 205, 206, 207,or 208 is changed to a third reduction mode l3. In the third reductionmode l3, the controller 200, 201, 202, 203, 204, 205, 206, 207, or 208fixes the operating frequency f_c to the second reference frequency f2,fixes the operating duty cycle d_c1 of the first leg (i.e., the on-dutycycle of the second control signal con24, con25, and con28 (FIGS. 11,12, and 15)) to the ping duty cycle d_p, and adjusts the operating dutycycle d_c2 of the second leg (i.e., the on-duty cycle of the fourthcontrol signal con44, con45, and con48 (FIGS. 11, 12, and 15)). In thethird reduction mode l3, the operating duty cycle d_c2 of the second legis varied within the range of the ping duty cycle d_p to (100−ping dutycycle d_p).

In the third reduction mode l3, when the amount of power received by thewireless power receiver 2 is greater than the amount of power requiredby the wireless power receiver 2, even in the case in which theoperating duty cycle d_c2 of the second leg is decreased up to the pingduty cycle d_p, the operation mode of the controller 200, 201, 202, 203,204, 205, 206, 207, or 208 is changed to the fourth reduction mode l4.In the fourth reduction mode l4, the controller 200, 201, 202, 203, 204,205, 206, 207, or 208 fixes the operating duty cycle d_c1 of the firstleg (i.e., the duty cycle of the second control signal con24, con25, andcon28 (FIGS. 11, 12, and 15)) to the ping duty cycle d_p, fixes theoperating duty cycle d_c2 of the second leg (i.e., the duty cycle of thefourth control signal con44, con45, and con48 (FIGS. 11, 12, and 15)) to100%, and adjusts the operating frequency f_c. In the fourth reductionmode l4, the operating frequency f_c is varied within the range of thesecond reference frequency f2 to the maximum frequency f_max.

That is, if the load amount is less than a second reference load amountR210 and is greater than a fourth reference load amount R410, thecontroller 200, 201, 202, 203, 204, 205, 206, 207, or 208 is operated inthe third reduction mode l3. If the load amount is less than the fourthreference load amount R410, the controller 200, 201, 202, 203, 204, 205,206, 207, or 208 is operated in the fourth reduction mode l4.

The control methods illustrated in each of FIGS. 27 through 46 may berecombined in various forms. For example, operations S3465 and S3485 ofFIG. 35 or the operation of the third boost mode h3 of FIG. 36 may alsobe added to the control methods of each of FIGS. 27 through 46.Alternatively, the third reduction mode illustrated in FIGS. 42 and 46and/or the fourth reduction mode illustrated in FIGS. 44 and 46 are alsoperformed instead of the first reduction mode and/or the secondreduction mode, according to another embodiment. Alternatively, in eachof FIGS. 27 through 46, the operations and the operation modes areperformed while some operations and some operation modes are omitted.

The control methods illustrated in FIGS. 27 through 46 are performedvariously based on the request signal input from the wireless powerreceiver 2.

For example, the ping frequency f_c is selected as the same frequency asthe first reference frequency f1. Thereafter, if it is determined, basedon the signal received from the wireless power receiver 2, that theamount of power received by the wireless power receiver 2 is less thanthe amount of power required by the wireless power receiver 2, theoperation in the first boost mode h1 according to the embodimentsdescribed above are also performed. Alternatively, if it is determined,based on the signal received from the wireless power receiver 2, if thatthe amount of power received by the wireless power receiver 2 is greaterthan the amount of power required by the wireless power receiver 2, theoperation in the normal mode n according to the embodiments describedabove are also performed.

Thereafter, based on the signal received from the wireless powerreceiver 2, at least one of the operations of the first boost mode h1,the second boost mode h2, the third boost mode h3, the normal mode n,the first reduction mode l1, the second reduction mode l2, the thirdreduction mode l3, and the fourth reduction mode l4, according to theembodiments described above are sequentially performed.

For example, in a case in which a battery of the wireless power receiver2 is in a state close to a discharge state, the wireless power receiver2 first requires a large amount of power, and then gradually requires asmaller amount of power as the battery is gradually charged. In thiscase, after the operation in the boost mode h1, h2, or h3 is performed,the operations in the normal mode n and the reduction mode l1, l2, l3,or l4 are sequentially performed.

Alternatively, in a case in which the battery of the wireless powerreceiver 2 is charged to some extent, the wireless power receiver 2requires a small amount of power from the beginning. Therefore, in thiscase, the operation in the reduction mode l1, l2, l3, or l4 areperformed first.

Alternatively, when an alignment state between the wireless powerreceiver 2 and the wireless power transmitter 1, 1-2, 1-3, 1-4, 1-5,1-6, 1-7, or 1-8 is distorted, the control is changed to a direction inwhich the load amount is increased in FIGS. 27 through 46. For example,when the alignment between the wireless power receiver 2 and thewireless power transmitter 1, 1-2, 1-3, 1-4, 1-5, 1-6, 1-7, or 1-8 isdistorted while the operation in the normal mode n or the operation inthe reduction mode l1, l2, l3, or l4 is performed, the operation in thenormal mode n or the operation in the boost mode h1, h2, or h3 may alsobe performed. Alternatively, when the alignment between the wirelesspower receiver 2 and the wireless power transmitter 1, 1-2, 1-3, 1-4,1-5, 1-6, 1-7, or 1-8 is distorted while the operation in the firstboost mode h1 is performed, the operation in the second boost mode h2may also be performed.

Alternatively, when the wireless power receiver 2 and the wireless powertransmitter 1, 1-2, 1-3, 1-4, 1-5, 1-6, 1-7, or 1-8 are sufficientlyaligned, the control is changed to a direction in which the load amountis decreased in FIGS. 27 through 46. For example, the operation in thereduction mode l1, l2, l3, or l4 may be performed while the operation inthe normal mode n is performed.

The control methods illustrated in FIGS. 27 through 46 are alsoperformed so that the frequency wirelessly transmitted belongs to areference range. For example, the controller 200, 201, 202, 203, 204,205, 206, 207, or 208 adjusts the duty cycle and the frequency of thecontrol signal while preferentially satisfying the conditions that thefrequency wirelessly transmitted is a reference value or less, is areference value or more, and belongs to a predetermined range.

FIG. 47 is a diagram illustrating a coil current and an output voltageof the wireless power transmitter 1, 1-2, 1-3, 1-4, 1-5, 1-6, 1-7, or1-8, according to an embodiment.

The thick dotted line of a graph (a) of FIG. 47 illustrates a coilcurrent of the resonator 120, 121, 122, 123, 124, 125, 126, 127, or 128,according to an embodiment illustrated in each of FIGS. 7 through 15,while a thin solid line of the graph (a) of FIG. 47 illustrates a coilcurrent according to a comparative example.

A thick dotted line of the graph depicted in FIG. 47B illustrates anoutput voltage, a voltage across the resonator 120, 121, 122, 123, 124,125, 126, 127, or 128, according to an embodiment illustrated in each ofFIGS. 7 through 15, and a thin solid line of the graph depicted in FIG.47B illustrates an output voltage according to a comparative example.

The comparative example is the wireless power transmitter including thefull-bridge inverter, operated by receiving the input power. In the caseof the comparative example, the input power is a power provided by theboost converter implemented separately from the inverter.

As illustrated, it can be confirmed that the wireless power transmitter1, 1-2, 1-3, 1-4, 1-5, 1-6, 1-7, or 1-8, according to an embodimentprovides the coil current and the output voltage corresponding to thefull-bridge inverter according to the comparative example, while usingthe half-bridge inverter.

FIG. 48 is a diagram illustrating a boost voltage and an output voltagebased on a change of a duty cycle in the wireless power transmitter 1,1-2, 1-3, 1-4, 1-5, 1-6, 1-7, or 1-8, according to an embodiment.

Graph (a) of FIG. 48 illustrates a boost voltage (a voltage of the nodeN2 of FIGS. 8 through 15), and graph (b) thereof illustrates an outputvoltage of the wireless power transmitter 1, 1-2, 1-3, 1-4, 1-5, 1-6,1-7, or 1-8.

In graph (a), a thick line illustrates the boost voltage based on a dutycycle of 50%, and a thin line illustrates the boost voltage based on aduty cycle of 70%.

As illustrated, it can be appreciated that the boost voltage based onthe duty cycle of 50% is about 10V, but the output voltage of theboosting unit based on the duty cycle of 70% is slightly higher than16V, which provides a higher boosting efficiency.

In addition, accordingly, as illustrated in graph (b), it can beappreciated that the output voltage of the wireless power transmitter 1,1-2, 1-3, 1-4, 1-5, 1-6, 1-7, or 1-8 based on the duty cycle of 50% isabout 5V, but the output voltage of the boosting unit based on the dutycycle of 70% is adjacent to 7V, which provides a higher output.

As set forth above, according to the embodiments in the disclosureherein, the wireless power transmitter 1, 1-2, 1-3, 1-4, 1-5, 1-6, 1-7,or 1-8 and the wireless power transmission method reduce the number ofcomponents required for manufacturing the wireless power transmitter,whereby a smaller-sized wireless power transmitter may be implementedand material costs thereof may be saved. Further, the wireless powertransmitter 1, 1-2, 1-3, 1-4, 1-5, 1-6, 1-7, or 1-8 and the wirelesspower transmission method according to the embodiments herein providesmore convenience to the user, such as increasing the range across whichthe power is wirelessly transmitted while satisfying various limitationsto be satisfied in wirelessly transmitting the power, and also improvewireless power transmission efficiency. Further, the wireless powertransmitter 1, 1-2, 1-3, 1-4, 1-5, 1-6, 1-7, or 1-8 and the wirelesspower transmission method according to the embodiments herein moreprecisely controls the power transmission, whereby the unnecessary powerconsumption is prevented and overheating of the wireless power receiver2 or damage to an element of the wireless power receiver 2 is alsoprevented. Further, the wireless power transmitter 1, 1-2, 1-3, 1-4,1-5, 1-6, 1-7, or 1-8 and the wireless power transmission method,according to the embodiments disclosed herein, reduces the inrushcurrent and the peak current that occur at the time of generating thesignal for determining whether the wireless power receiver is present,whereby the operation in the detection mode for determining whether thewireless power receiver is present is stabilized.

The controllers 200, 201, 202, 203, 204, 205, 206, 207 and 208 in FIGS.7 through 15 that perform the operations described in this applicationare implemented by hardware components configured to perform theoperations described in this application that are performed by thehardware components. Examples of hardware components that may be used toperform the operations described in this application where appropriateinclude controllers, sensors, generators, drivers, memories,comparators, arithmetic logic units, adders, subtractors, multipliers,dividers, integrators, and any other electronic components configured toperform the operations described in this application. In other examples,one or more of the hardware components that perform the operationsdescribed in this application are implemented by computing hardware, forexample, by one or more processors or computers. A processor or computermay be implemented by one or more processing elements, such as an arrayof logic gates, a controller and an arithmetic logic unit, a digitalsignal processor, a microcomputer, a programmable logic controller, afield-programmable gate array, a programmable logic array, amicroprocessor, or any other device or combination of devices that isconfigured to respond to and execute instructions in a defined manner toachieve a desired result. In one example, a processor or computerincludes, or is connected to, one or more memories storing instructionsor software that are executed by the processor or computer. Hardwarecomponents implemented by a processor or computer may executeinstructions or software, such as an operating system (OS) and one ormore software applications that run on the OS, to perform the operationsdescribed in this application. The hardware components may also access,manipulate, process, create, and store data in response to execution ofthe instructions or software. For simplicity, the singular term“processor” or “computer” may be used in the description of the examplesdescribed in this application, but in other examples multiple processorsor computers may be used, or a processor or computer may includemultiple processing elements, or multiple types of processing elements,or both. For example, a single hardware component or two or morehardware components may be implemented by a single processor, or two ormore processors, or a processor and a controller. One or more hardwarecomponents may be implemented by one or more processors, or a processorand a controller, and one or more other hardware components may beimplemented by one or more other processors, or another processor andanother controller. One or more processors, or a processor and acontroller, may implement a single hardware component, or two or morehardware components. A hardware component may have any one or more ofdifferent processing configurations, examples of which include a singleprocessor, independent processors, parallel processors,single-instruction single-data (SISD) multiprocessing,single-instruction multiple-data (SIMD) multiprocessing,multiple-instruction single-data (MISD) multiprocessing, andmultiple-instruction multiple-data (MIMD) multiprocessing.

The methods illustrated in FIGS. 2, 3 and 16 through 48B that performthe operations described in this application are performed by computinghardware, for example, by one or more processors or computers,implemented as described above executing instructions or software toperform the operations described in this application that are performedby the methods. For example, a single operation or two or moreoperations may be performed by a single processor, or two or moreprocessors, or a processor and a controller. One or more operations maybe performed by one or more processors, or a processor and a controller,and one or more other operations may be performed by one or more otherprocessors, or another processor and another controller. One or moreprocessors, or a processor and a controller, may perform a singleoperation, or two or more operations.

Instructions or software to control computing hardware, for example, oneor more processors or computers, to implement the hardware componentsand perform the methods as described above may be written as computerprograms, code segments, instructions or any combination thereof, forindividually or collectively instructing or configuring the one or moreprocessors or computers to operate as a machine or special-purposecomputer to perform the operations that are performed by the hardwarecomponents and the methods as described above. In one example, theinstructions or software include machine code that is directly executedby the one or more processors or computers, such as machine codeproduced by a compiler. In another example, the instructions or softwareincludes higher-level code that is executed by the one or moreprocessors or computer using an interpreter. The instructions orsoftware may be written using any programming language based on theblock diagrams and the flow charts illustrated in the drawings and thecorresponding descriptions in the specification, which disclosealgorithms for performing the operations that are performed by thehardware components and the methods as described above.

The instructions or software to control computing hardware, for example,one or more processors or computers, to implement the hardwarecomponents and perform the methods as described above, and anyassociated data, data files, and data structures, may be recorded,stored, or fixed in or on one or more non-transitory computer-readablestorage media. Examples of a non-transitory computer-readable storagemedium include read-only memory (ROM), random-access memory (RAM), flashmemory, CD-ROMs, CD-Rs, CD+Rs, CD-RWs, CD+RWs, DVD-ROMs, DVD-Rs, DVD+Rs,DVD-RWs, DVD+RWs, DVD-RAMs, BD-ROMs, BD-Rs, BD-R LTHs, BD-REs, magnetictapes, floppy disks, magneto-optical data storage devices, optical datastorage devices, hard disks, solid-state disks, and any other devicethat is configured to store the instructions or software and anyassociated data, data files, and data structures in a non-transitorymanner and provide the instructions or software and any associated data,data files, and data structures to one or more processors or computersso that the one or more processors or computers can execute theinstructions. In one example, the instructions or software and anyassociated data, data files, and data structures are distributed overnetwork-coupled computer systems so that the instructions and softwareand any associated data, data files, and data structures are stored,accessed, and executed in a distributed fashion by the one or moreprocessors or computers.

As a non-exhaustive example only, an electronic device as describedherein may be a mobile device, such as a cellular phone, a smart phone,a wearable smart device (such as a ring, a watch, a pair of glasses, abracelet, an ankle bracelet, a belt, a necklace, an earring, a headband,a helmet, or a device embedded in clothing), a portable personalcomputer (PC) (such as a laptop, a notebook, a subnotebook, a netbook,or an ultra-mobile PC (UMPC), a tablet PC (tablet), a phablet, apersonal digital assistant (PDA), a digital camera, a portable gameconsole, an MP3 player, a portable/personal multimedia player (PMP), ahandheld e-book, a global positioning system (GPS) navigation device, ora sensor, or a stationary device, such as a desktop PC, ahigh-definition television (HDTV), a DVD player, a Blu-ray player, aset-top box, or a home appliance, or any other mobile or stationarydevice. In one example, a wearable device is a device that is designedto be mountable directly on the body of the user, such as a pair ofglasses or a bracelet. In another example, a wearable device is anydevice that is mounted on the body of the user using an attachingdevice, such as a smart phone or a tablet attached to the arm of a userusing an armband, or hung around the neck of the user using a lanyard.

While this disclosure includes specific examples, it will be apparentafter an understanding of the disclosure of this application thatvarious changes in form and details may be made in these exampleswithout departing from the spirit and scope of the claims and theirequivalents. The examples described herein are to be considered in adescriptive sense only, and not for purposes of limitation. Descriptionsof features or aspects in each example are to be considered as beingapplicable to similar features or aspects in other examples. Suitableresults may be achieved if the described techniques are performed in adifferent order, and/or if components in a described system,architecture, device, or circuit are combined in a different manner,and/or replaced or supplemented by other components or theirequivalents. Therefore, the scope of the disclosure is defined not bythe detailed description, but by the claims and their equivalents, andall variations within the scope of the claims and their equivalents areto be construed as being included in the disclosure.

What is claimed is:
 1. A wireless power transmitter, comprising: aconverter comprising at least one switching element, and configured togenerate boosted input power; a resonator configured to receive theboosted input power as an alternating current (AC) power, and transmit aping signal in a detection mode for determining whether any one or bothof an external object approaching and a type of the external object; anda controller configured to control the switching element, and graduallyincrease a duty cycle of a gate signal provided to the switchingelement, in the detection mode.
 2. The wireless power transmitter ofclaim 1, wherein the controller gradually increases the duty cycle ofthe gate signal in an amount equal to a reference duty cycle.
 3. Thewireless power transmitter of claim 2, wherein the controller increasesthe duty cycle of the gate signal from a first duty cycle of 0%, in aninitial operation mode of the detection mode.
 4. The wireless powertransmitter of claim 3, wherein the initial operation mode correspondsto a mode for transmitting the ping signal in a stop state for a timeequal to or greater than a reference time.
 5. The wireless powertransmitter of claim 3, wherein the controller increases the duty cycleof the gate signal to a ping duty cycle, and the boosted input power toreach a target boosted input power for generating the ping signal in theping duty cycle.
 6. The wireless power transmitter of claim 5, whereinthe controller is further configured to calculate data on a voltagelevel of the boosted input power gradually increasing to the targetboosted input power, and a duty cycle corresponding to the voltage levelof the boosted input power gradually increases.
 7. The wireless powertransmitter of claim 6, wherein the controller is further configured toincrease the duty cycle of the gate signal from a second duty cycle, ina standby operation mode of the detection mode, and the second dutycycle is determined based on the voltage level of boosted input power.8. The wireless power transmitter of claim 7, wherein the standbyoperation mode corresponds to a mode for transmitting a ping signal inthe stop state for less than the reference time.
 9. The wireless powertransmitter of claim 7, wherein the voltage level of the boosted inputpower is estimated based on a period of the ping signal.
 10. Thewireless power transmitter of claim 7, wherein the second duty cycle iscalculated based on the voltage level of the boosted input power and thedata.
 11. The wireless power transmitter of claim 10, wherein the secondduty cycle is determined by applying a weighted index, calculated bycomparing a voltage level of the target boosted input power to thevoltage level of the boosted input power, to the ping duty cycle. 12.The wireless power transmitter of claim 10, wherein the data is providedin the form of a lookup-table, and the second duty cycle is determinedby searching through the lookup-table for a duty cycle corresponding tothe voltage level of the boosted input power.
 13. A wireless powertransmitter operated in a detection mode including a first mode and asecond mode, and transmitting a ping signal in the detection mode, thetransmitting wireless power transmitter, comprising: a convertercomprising at least one switching element, and configured to convertinput power into boosted input power based on a switching operation ofthe switching element, and output the boosted input power as analternating current (AC) power; a resonator configured to generate theping signal from the AC power; and a controller configured to controlthe switching element, increase a duty cycle of a gate signal providedto the switching element from a first duty cycle in the first mode, andincrease a duty cycle of the gate signal from a second duty cycle higherthan the first duty cycle in the second mode.
 14. The wireless powertransmitter of claim 13, wherein the controller is further configured toincrease the duty cycle of the gate signal to a ping duty cycle in thefirst mode, and the boosted input power reaches a target boosted inputpower for generating the ping signal in the ping duty cycle.
 15. Thewireless power transmitter of claim 14, wherein the second duty cycle isdetermined based on a weighted index, calculated by comparing a voltagelevel of the target boosted input power to a voltage level of theboosted input power, to the ping duty cycle.
 16. The wireless powertransmitter of claim 13, wherein the switching element is configured toperform a converting operation from the boosted input power to the inputpower and an outputting operation from the boosted input power as ACpower.
 17. A wireless power transmitter, comprising: a converterconfigured to generate an alternating current (AC) voltage; a resonatorconfigured to receive the AC voltage, and transmit a ping signal fordetermining whether an external object is within proximity; and acontroller configured, in a detection mode, to control the switchingelement, and increase a duty cycle of a gate signal provided to theswitching element by a step size from a first duty cycle to a targetduty cycle.
 18. The wireless power transmitter of claim 17, where thestep size is an integer.
 19. The wireless power transmitter of claim 18,wherein the first duty cycle is 0%.
 20. The wireless power transmitterof claim 18, wherein an initial operation mode corresponds to a mode fortransmitting the ping signal in a stop state for a time equal to orgreater than a reference time.